Uncorrected Sample Pages NCEA Level 2 THETA MATHEMATICS DAVID BARTON rig py co ly - The Theta Mathematics package Foreword to students, parents and teachers Investigations Puzzles CAS calculator applications Simulations ht Pe ar s CONTENTS on THINK THETA Co-ordinate geometry Further co-ordinate geometry ra ft 1 2 on 2.1 Co-ordinate geometry 3 4 5 6 7 8 D 2.2 Graphical models Polynomials and their graphs Functions – domain and range Other mathematical functions and their graphs Transformations of graphs and the connection with parameters Trigonometric graphs Piecewise graphs iv vi viii viii ix ix 1 2 15 34 35 49 62 91 104 134 2.4 Trigonometric relationships 142 9 10 11 12 143 159 170 186 Triangle trigonometry The sine rule The cosine rule Circular measure 2.6 Algebraic methods 207 13 209 9781442549487_PRELIMS.indd 2 Basic algebra 6/13/11 6:24 AM on ar s ht Pe - co py rig Algebraic fractions Factorising and quadratic expressions Solving equations and rearranging formulae Quadratic equations Exponential expressions Logarithms 225 231 240 252 271 283 294 20 21 22 23 Introducing differentiation Calculus and curves Anti-differentiation Calculus applications 295 307 319 340 2.12 Probability methods 359 24 25 26 Probability Further probability The normal distribution 360 378 395 ra ft on ly 2.7 Calculus methods D 14 15 16 17 18 19 2.13 Simulation 437 27 438 Simulation methods 2.14 Systems of equations 459 28 29 460 468 Simultaneous equations Non-linear simultaneous equations A nswers Index Useful formulae Normal distribution table 9781442549487_PRELIMS.indd 3 482 564 566 574 6/13/11 6:24 AM iv The Theta Mathematics package ra ft on ly - co py rig ht Pe ar s on 2.1 Theta Mathematics has been completely updated to reflect the current requirements of Mathematics and Statistics in the New Zealand Curriculum. It has been reorganised to provide full coverage of the 14 Level 2 Mathematics and Statistics Achievement Standards that, in 2012, replace the earlier nine. Most students enter for only six or seven of these Achievement Standards in any given year. This means that, effectively, they are only covering about half the curriculum in a year-long course and, therefore, they can study topics in more depth. Their learning resources need to be comprehensive and offer a wide spectrum of skills, challenges and interpretation-type problems. Moreover, schools now have the flexibility to offer a partial Level 2 course to Year 11 students or to allow students, in some cases, to gain Level 2 NCEA credits over two years. Therefore, for modern classrooms, the traditional ‘one size fits all’ textbook is not appropriate. Not only would most students use just half of it, but a textbook that covered all 14 Achievement Standards would either be hopelessly overweight or, if its size were kept in bounds, would skim over topics without doing them full justice. Our challenge is to provide a solution that meets the needs of students and schools, offering them flexibility and not dictating a particular course. At the same time, all 14 Achievement Standards have to be covered comprehensively and rigorously so that school communities can have confidence that students are well prepared for assessment. We also have to bear in mind the growing number of schools who expect to deliver the curriculum and learning resources digitally and want the opportunity to select the particular combination of modules from the Theta Mathematics package that meets their needs. The two-path solution we offer is aimed at several groups of students: • students planning to do mathematics in Year 13, and therefore requiring a course that offers the appropriate prerequisites for Level 3 Calculus and/or Level 3 Statistics • students wanting to gain some NCEA Level 2 credits in Year 11 • students aiming for a full collection of Level 2 Mathematics credits spread over a two-year period. The table shows how the 14 Achievement Standards fit into the two textbooks at the centre of the package. Theta Dimensions 2.1 2.2 2.4 2.6 2.7 2.12 2.13 2.14 2.2 2.3 2.4 2.5 2.8, 2.9, 2.10 2.11 2.12 2.13 D Theta Mathematics Co-ordinate geometry Graphical models Trigonometric relationships Algebraic methods Calculus methods Probability methods Simulation Systems of equations 9781442549487_PRELIMS.indd 4 Graphical models Sequences and series Trigonometric relationships Networks Statistical investigation Statistical report Probability methods Simulation 6/13/11 6:24 AM The Theta Mathematics package v Theta Mathematics: • • • • • includes the topics that lead on to more advanced mathematics in Year 13 includes the topics that are currently assessed externally provides complete foundations for NCEA Level 3 Calculus provides a thorough preparation for the more demanding parts of NCEA Level 3 Statistics is the best choice for students who want to leave their options open so that they can take either or both of Level 3 Calculus and Level 3 Statistics. Theta Dimensions: includes the few topics that tend to terminate at this level offers a mathematically worthwhile course fully at NCEA Level 2 standard provides all the prerequisites and background needed for NCEA Level 3 Statistics is a good choice for students who may want to take statistics in Year 13. Each textbook contains a broad selection of Achievement Standards – more than the six that most students will enter – which means a particular course is not dictated by either textbook. Each textbook has an accompanying workbook (Theta Mathematics Workbook and Theta Dimensions Workbook). Furthermore, all four printed publications have a single, overarching, digital teaching resource (Theta Mathematics Teaching Resource) that supports them all. 2.1 2.2 2.4 2.6 D ra ft on ly - co py rig ht Pe ar s on • • • • 2.7 2.12 Dedication This book is dedicated to my brother, John Campbell Barton. 2.13 In loving memory of John, 9 December 1952–21 June 2005 2.14 Who would true valour see, let him come hither David Barton 9781442549487_PRELIMS.indd 5 6/13/11 6:24 AM vi Foreword to students, parents and teachers D ra ft on ly - co py rig ht Pe ar s on Welcome to Year 12 and another year of learning mathematics. This textbook will provide you with full coverage of the following NCEA Mathematics Level 2 Achievement Standards: 2.1, 2.2, 2.4, 2.6, 2.7, 2.12, 2.13 and 2.14. Features to particularly note in the treatment of these Achievement Standards include the following: • expanded coverage of geometric reasoning in Achievement Standard 2.1 • new material on functions, and domain and range in Achievement Standard 2.2 • new material on piecewise functions in Achievement Standard 2.2 • more emphasis on key features of graphs in Achievement Standard 2.2 • completing the square has been added in Achievement Standard 2.6 • graphs of derived functions are now covered in Achievement Standard 2.7 • a new section on relative risk in Achievement Standard 2.12 •full explanations of how to use appropriate technology to carry out normal probability calculations in Achievement Standard 2.12, and normal distribution tables have been included in an appendix to save teachers from having to provide separate books of tables. As you can see by looking at the edge of this textbook, each Achievement Standard has its own coloured section so that you know exactly which topics fit where! Each section has full explanations, worked examples and plenty of exercises so that you can learn new skills and solve mathematical problems, with a solid and comprehensive core of graded, skill-based problems as in previous editions. Where relevant, the activities are carefully integrated with application-style questions in contexts that relate to students’ experiences. Updated features of this edition of Theta Mathematics include: • liberal and functional use of colour • new application questions added throughout • full emphasis on using relevant technology •new investigations and puzzles, as well as many of the popular ones from the previous edition •spreadsheets that can be downloaded from the companion website, www.mathematics.co.nz •tags on the edge of each page for easy navigation between exercise questions and answers • references to CAS activities, where appropriate. Year 12 is where students first begin to study mathematics in some depth. Until this stage, much of mathematics has been applications-based, with some straightforward skills work. Now, students start to learn about some of the underlying structure of mathematics and study it for its own sake. At this level, mathematics is an optional subject, and we can assume that most students using this textbook have enjoyed doing mathematics so far. My aim in updating this textbook has been to continue to stimulate students’ interest and encourage them to carry on with mathematical studies. Topics that students are meeting for the first time, such as calculus and the normal distribution, are accompanied by a large number of graded, skills-based questions intended to reinforce students’ understanding and build solid foundations for future learning. Full and comprehensive answers are provided. In most cases, for questions involving numerical working, answers are correct to four significant figures so that students can check whether their calculations are accurate. In some cases, however, answers have been rounded appropriately to fit the context of the question. 9781442549487_PRELIMS.indd 6 6/13/11 6:24 AM Foreword to students, parents and teachers Although this textbook has been organised around the NCEA Level 2 Achievement Standards listed above, it also provides carefully planned coverage of selected mathematics and statistics achievement objectives in the New Zealand Curriculum. NCEA is about assessing the curriculum – but it is also important to provide a course that lays solid foundations for future study and builds on mathematics covered earlier. Theta Mathematics and its sister textbook, Theta Dimensions, both follow a ‘spiral’ and integrated approach to learning mathematics – revisiting topics frequently to reinforce earlier understanding, and gradually increasing the difficulty level. The treatment of topics in these textbooks addresses the fact that the strands in NCEA, although assessed separately, are inter-related in many places. ARTER rig ht Pe ar s INVESTIGATION Advice to students Mathematics is a subject you learn by doing. You will feel more confident about it when you have attempted a wide range of problems. The exercises in this textbook have been graded so that the easier ones come first. Check the answers frequently as you go, to get feedback on whether you understand the process. Use the tags on the edge of each page to help you navigate between the exercise questions and the answers. Write as much working as possible – this makes it easier for someone else to check your understanding, and explain where you need help. Do not become discouraged if you make careless mistakes sometimes – some of the most famous mathematicians have been hopeless at telling the time or managing money! Throughout the textbook, you will find a variety of investigations, puzzles and spreadsheet activities. Try doing these – you will be surprised at how often interesting mathematics is found in unexpected and unfamiliar situations. You will probably use this textbook mainly in the classroom. However, you need to study and do extra activities in your own time to do as well as possible. The Theta Mathematics Workbook is ideal for this purpose. It provides full homework and revision for the course, with plenty of NCEA-style questions. The workbook is closely referenced to this textbook, making it really easy to match homework and revision with what you are doing in class. Because the workbook is a ‘write-on’ publication, you can add your own notes, highlight important points, colour-code places where you made mistakes for future reference or add hints from your teacher. The Theta Mathematics Workbook also features a student CD, which includes key worked examples from the textbook, all the spreadsheets referred to in this textbook, and links to internet websites. Mathematics will lie behind much of your career and journey through life. With a broad mathematics education and a positive attitude, you should do well. Best wishes for an enjoyable, challenging and successful year. David Barton on STARTER ST vii T I P TIP D ra ft on ly - TEACHER co py PUZZLE B C TECH TECHNOLOGY 9781442549487_PRELIMS.indd 7 A S CAS CALCULATOR DATA DATA SET L M BLACKLINE MASTER 6/13/11 6:24 AM viii INVESTIGATIONS on ar s Pe py rig 124 140 146 154 157 172 174 177 181 190 196 205 213 234 Hollow squares Three squares in a row Floor joists Play and rewind The Golden Ratio Quadratic equation solver Tartaglia and Cardano The pendulum The Towers of Hanoi The shrinking chord Combining trapeziums The warehouse The horse-breeder’s paddock Fifty cents and the polar bears Coffee cups The normal curve and the witch of Agnesi Off to the freezing works The acoustic concert hall ht 48 58 70 85 90 112 237 239 244 251 262 265 270 273 280 298 331 351 358 394 404 425 463 481 ra ft on ly - co The roller-coaster Reading age The dance floor Exponential and logarithmic graphs Different bases, different curves Producing trig graphs on a spreadsheet Modelling monthly temperatures in Clyde, Central Otago Room numerals The Cairo pentagon Square roots and trigonometry What is the value of tan(90°)? Pythagoras and the cosine rule The octagon chop The Golden Ratio and the cosine rule Maximising the apparent width The Polygon Society and the round tablecloth The Auckland–Sydney road tunnel The Reuleaux triangle Chequered flags Splitting rectangles D Wayward perpendicular bisectors The stolen bicycle Circumscribed triangle Double triangles The mobile crane Straight hands The pool ball triangle The lune The cucumber puzzle The third highest number The four friends Stuffing envelopes Xavier and Yvonne The shoemaker’s will The grandstand 9781442549487_PRELIMS.indd 8 PUZZLES 29 33 153 179 185 190 193 203 205 216 218 222 224 227 233 Filling the bath A windy day The bicycle puncture Pumpkin patch Minding your ps and qs The model railway This century base 3 Fours galore Car number plates Last digit Two and two make five The white marbles Two flat tyres – tow me home! The chocolate rabbits Penny wise, pound foolish The Boeing 757 The great picnic puzzle 241 246 248 257 260 265 272 273 275 278 279 369 373 463 463 464 467 6/13/11 6:25 AM ix A S CAS CALCULATOR APPLICATIONS Applications of linear rearrangements Applications of index equations Multiples of powers of x Differentiating simple products and quotients Finding the point where the gradient has a given value The rule for anti-differentiation of polynomials Definite integrals 242 290 300 301 308 334 397 411 416 429 468 ra ft D 9781442549487_PRELIMS.indd 9 rig The licorice factory and the triangle inequality Ten to one it’s Pythagoras The cars and the goat (the Monty Hall problem) Normally distributed values Heights of children Volumes of soft drinks Excess baggage charges Cats and mice (predator–prey) Sharks and fish (predator–prey) Ferrets and fantails (predator–prey) Off-road vehicles and toheroa (predator–prey) co py <••> <••> <••> <••> <••> <••> <••> <••> <••> <••> <••> <••> <••> ly on Fifty cents and the polar bears Tossing a fair coin Waiting for heads Fives and sixes The petrol station and the coloured cards The World Series Boys and girls Three members of a family The gamblers The Chinese Lunar Calendar The Zodiac The dartboard The overbooked car-ferry ht SIMULATIONS Pe ar s 319 328 Applications of area Using technology to find the standard deviation Using technology to calculate standard normal probability Using technology to calculate any normal probability Using technology to obtain normal ‘inverses’ Intersection of lines and curves on C <••> <••> <••> <••> <••> <••> <••> <••> <••> <••> <••> 6/13/11 6:25 AM 24 2.1 Co-ordinate geometry Intersection of lines Some topics in mathematics blend algebra and geometry together. When working out where lines intersect, you can use: • geometry − draw the lines and inspect the graph to locate the point of intersection, or • algebra − solve a pair of simultaneous equations, where each equation represents one of the lines. The approach here uses methods that are also covered in Achievement Standard 2.6: Equations and expressions. Ideally, when locating the intersection of two lines, consider a combined approach: • drawing a graph to get an approximate idea of the location • using algebra to determine the exact co-ordinates. Pairs of lines do not always intersect on the grid (with integer values) and, in some cases, only algebra will give you the exact values. co py rig Example Determine the point of intersection of the two lines: 5x − 2y − 10 = 0 3x + y − 4 = 0. ht Pe ar s T I P on 2 C A S D ra ft on ly - Answer Use technology or otherwise to draw the graph of both lines on the same grid. Note that the technology may require you to enter the equations of the lines in the form of y = mx + c: y = 5 x + 5 (1) 2 − y = 3x + 4 (2) The graph shows that the lines intersect near the point (1.5, −1). We can use the ‘Trace’ function on a CAS calculator to obtain a very accurate estimate. 9781442549487_CH-2.indd 24 6/12/11 6:23 AM 56 2.2 Graphical models Absolute value The absolute value of a number can be thought of as its size or the distance it is from 0 on a number line. We always take distance as being non-negative. The absolute value function is written as f(x) = |x|. • If x < 0, then |x| = −x, making it positive. • If x ≥ 0, then |x| = x (so that it stays non-negative). The effect of the absolute value brackets | … | is that they make the result of the expression inside y positive if it is negative. Answers a 3 Note that the domain, or set of possible x-values, for |x| is the real numbers, R. The range of f(x) = |x| is {y: y ≥ 0, y ∈ R}. ht The term ‘graphing software’ here is very broad. It could include the use of graph-drawing programs, a graphics calculator, a spreadsheet or a CAS calculator. The graphs can also be drawn by hand. ra ft on ly - T I P From a spreadsheet: TECH co Example Use graphing software to draw the graph of f(x) = |x + 3| − 5. Identify the key features of the graph, including the domain, the range and any intercepts. Pe ar s c 7 x rig b 14 on The graph of the absolute value function has only non-negative y-values: py 4 Examples Evaluate the following. a |−3| b |14| c |10 − 17| D Answer On a CAS calculator: C A S Note that the command for absolute value is ABS( ). 9781442549487_CH-4.indd 56 Note that the formula for the absolute value of the number in any cell, e.g. B1, is =ABS(B1). The domain is all the real numbers, R, because there are no restrictions on the values of x. The range is y ≥ −5. The y-intercept is (0, −2). The x-intercepts are (−8, 0) and (2, 0). The vertex of this absolute value graph is (−3, −5). 6/12/11 6:26 AM 139 8 Piecewise graphs 3 The outline of a symmetrical arch design can be modelled by two parabolas. The design starts at a height of 6 m above the ground and is 6 m wide at the bottom. The height, h, in metres of the design above the ground can be modelled by a piecewise function, where x is the distance in metres from the left edge. −1 x 2 + 2x + 6, h(x) = 4 −1 2 4 x + px + q, 0≤x≤k on k≤x≤6 a What is the value of k? bCalculate the height above ground level of the top of the design. c What are the values of p and q? dExplain whether the two parts of the design meet at an angle or as part of a smooth curve. ar s Pe ht rig py co aCalculate the pressure at the time when the leak occurs. bWhen t = 38 seconds, the pressure is 100 kPa. Use this information to write the equation of the hyperbola (that is, find the values of a and b). cWrite the equation of the horizontal asymptote of the hyperbola. Explain what this asymptote represents in the context of this model. - t Time (seconds) ly Straight line:P = 11t for values of t between 0 and 20. Hyperbola: P = a for values of t greater t−b than 20. 8 on P Tyre pressure (kPa) 4 A tyre-fitter is testing a tyre to check whether it is faulty. The tyre inflates normally and then a leak occurs. The pressure (P) in kPa (kilopascals) can be modelled by a straight line and a hyperbola. D ra ft 5 Under ideal conditions, a rat population increases at 25% per month. After five months, some bait is laid that contains a contraceptive (birth control) substance and, one month after that, the population starts to decrease by 10% per month. The curves and line in the diagram have the following equations: 2 y = p 3 y = k(0.9)x for values of x < 5 for values of x between 5 and 6 for values of x > 6. aUse equation 1 to calculate the maximum population and hence, find the value of p. bUse the graph to estimate the two times (to the nearest month) when the population is 400 rats. cExplain what you would expect to happen to the population of rats eventually, assuming equation 3 continues to apply. In your answer, mention a property of an exponential curve. dCalculate the value of k. 9781442549487_CH-8.indd 139 2 700 Population 1 y = 200(1.25)x 600 500 3 1 400 300 200 100 0 2 4 6 8 10 12 14 Time (months) 6/13/11 7:54 AM 146 2.4 Trigonometric relationships 23 A and B are two points on the circumference of a circle with centre O. C is a point on OB such that B AC ^ OB. A 5 cm AC = 12 cm 12 cm C and BC = 5 cm. Calculate the size of ∠AOB, marked q on the diagram. 24 A square with side length 5 cm is sitting on top of a square with side length 12 cm, as shown in the diagram. 5 cm What is the area of the blue quadrilateral? 12 cm on O INVESTIGATION ar s The Cairo pentagon Pe The diagram shows a tessellation made up of identical equilateral pentagons. It is reputedly named after Cairo, the capital of Egypt, because the streets there feature similar tiling patterns. ht 9 rig 1 Explain why the Cairo pentagon is not regular. - co py 2 Two of the angles of the Cairo pentagon are 90°. Calculate the sizes of the other three. Note: none of the other three angles is 120°! ly Applications of right-angled triangles D ra ft on Right-angle trigonometry has many applications: • navigation • building • surveying • civil engineering. Example When roads go round bends, engineers design them with a ‘camber’. The camber makes it easier for cars to stay on the road when cornering. At one place on a curve, a road has a camber of 4° and is 6.6 m across. Calculate the difference in height between the sides of the road. Answer There is enough information in the diagram to draw a right-angled triangle. The difference in heights is marked x. Use the sin formula. 9781442549487_CH-9.indd 146 o = h × sin(A) x = 6.6 × sin(4°) = 0.46 m (2 sf) x 6.6 m 4° 6/13/11 8:57 AM 12 Circular measure 203 PUZZLE The lune A lune is a figure shaped like a crescent moon. In plane geometry, a lune is a region bounded by two arcs. Calculate the area of the lune shown in the diagram. The centres of the two arcs that define the lune are at A and B. B is the midpoint of CD. × D B 6 cm 6 cm on C ar s A 4 A convex lens is designed so that its crosssection is represented by the intersecting part of two circles, each with a radius of 110 mm. The arcs on the edge of the lens subtend angles of 49° at the centre of each circle. Calculate the area of the cross-section, to the nearest mm2. co py 1 A stage at a theatre has the shape of a segment with a centre angle of 3 radians and a radius of 10 m. Calculate the area of the stage. 12 ht 12.07 rig EXERCISE Pe Applications of the area of a segment Convex lens 49° 49° 110 mm D ra ft on ly - 2 The diagram here shows the cross-section of a lens. The lens has been cut from a sphere with a radius of 400 mm, and the angle at the centre of the sphere subtending the arc is 0.21 radians. Calculate the area of the crosssection. 3 An equilateral triangle has sides of 10 cm. A circle (circumcircle) passes through all three vertices of the triangle. a Calculate the radius of the circumcircle. bCalculate the total area of all three segments formed by the triangle and circumcircle. 9781442549487_CH-12.indd 203 5 Two circles overlap as shown below. The radius of one circle is 50 cm, and the radius of the other circle is 70 cm. The length of the chord common to both is 30 cm. Calculate (to 2 sf) the area that lies in both circles. 30 cm 6/13/11 1:06 AM Calculate the volume of the prism. Pe ar s on 8 The photo shows a C cylindrical fuel tank. The S A diameter of the tank is 4 m. When the volume of fuel drops below 20% full, then more fuel should be ordered. What is the depth of fuel in the tank when it is 20% full? Give your answer to the nearest cm. ht 6 A road tunnel has a crosssection that can be modelled by a major segment 3m 3m of a circle with 2.3 radius 3 m. Tunnel floor The tunnel floor subtends an angle of 2.3 radians at the centre of the circle. The tunnel is straight and is 68 m long. aCalculate the height of the top of the tunnel above the tunnel floor. bCalculate the width of the tunnel floor. cEstimate the volume of earth and rock removed to construct the tunnel. Give your answer to the nearest hundred m3. Show your working and explain what you are calculating at each step. dExplain why the estimate may not be very accurate. co py 12 2.4 Trigonometric relationships rig 204 D ra ft on ly - 7 A prism has a cross-section made up of an isosceles trapezium and a segment, as shown in the diagram. • The centre of the segment is at the intersection of the diagonals of the trapezium, and the radius is 4.5 m. • The isosceles trapezium has parallel sides measuring 7.2 m and 4.8 m, with a distance of 4.5 m between the parallel sides. • The depth of the prism is 3 m. 3m 7.2 m 4.5 m 4.5 m 4.5 m 3m 4.8 m 9781442549487_CH-12.indd 204 4m Fuel (tank is 20% full) d Note: to determine the required depth, you will need either to use a CAS calculator that solves equations involving the formula for the area of a segment, or to use ‘guess and check’ methods; and then use trigonometry. 9 Two circles overlap so that the centre of each ×O one lies on the O1 × 2 circumference of the other. Each circle has a radius of 10 cm. Calculate the area of the intersection, shaded orange in the diagram. 6/13/11 1:07 AM 17 Quadratic equations 265 PUZZLE The model railway ar s on 32 m A model railway runs on a circular track inside a square section of land. The railway is adjacent to all four sides of the square and the closest it runs to any corner of the square is 32 m. Determine the area of the square section of land. Give your answer to the nearest m2. INVESTIGATION Pe Quadratic equation solver 17 ly - co py rig ht Let’s create a spreadsheet that automatically solves quadratic equations (in the form ax2 + bx + c = 0) when we type in the values of a, b and c into columns A, B and C. We’ll use columns D and E for the two solutions. The spreadsheet extract shows what the headings and part of the first row should look like. −b + b 2 − 4ac . 2a ra ft x= on The formula for the first root is: D Using cell references, we enter a similar formula in cell D3: =(-B3+SQRT(B3^2–4*A3*C3))/(2*A3) 1 Open a spreadsheet program and type in the headings and the values 1, 4 and -7 (for the first equation) in cells A3, B3 and C3. 2 Enter the formula in cell D3. If you don’t get the value 1.31662479, check that you have typed the formula correctly! 3 Write the formula for the second root. Enter it in cell E3. What value do you get? 4 Enter the values of a, b and c for equations 2–10 in the block of cells A4:C12. 5 Copy the formulae in cells D3 and E3 downwards nine times. Here are the 10 quadratic equations we will solve using the spreadsheet. 1 x2 + 4x - 7 = 0 2 3x2 + x - 8 = 0 3 8x2 - 24x - 23 = 0 4 x2 - 14x + 49 = 0 5 2x2 + 8x + 21 = 0 6 9x2 + 6x + 1 = 0 7 -6x2 8 x2 9 6x2 10 x2 -x-8=0 + 5x - 6 = 0 - 5x - 3 = 0 +x+1=0 6 Print out the result. 9781442549487_CH-17.indd 265 6/11/11 7:51 PM 304 2.7 Calculus methods Notice that: • f ′(x) is 0 between 0 and 10, and also between 40 and 50 – this is where the track is level • when the roller coaster is going up (height increasing), the gradient function f ′(x) is positive • when the roller coaster is going down (height decreasing), the gradient function f ′(x) is negative. The best place to draw the derived function graph, or gradient graph, is immediately below the function graph. Example on y f(x) = x2 x Pe ar s f ′(x) = 2x rig ht x co py The equation of the function need not be known to sketch the graph of the derived function. Just examine the graph of the original f(x) function, and read off or estimate the gradient at various x-values. Then transfer the value of the gradient to the corresponding x-value below. Example - f(x) ly 20 y –2 f′(x) ra ft 2 y=x+2 4 D y=1 T I P 9781442549487_CH-20.indd 304 on y = x2 – 8x + 18 y=2 x y = 2x – 8 x Proceeding from left to right: •the first part of f(x) has a gradient of 1 so, below this part of the function, we draw the graph of y = 1 •then, the horizontal portion of the graph of f(x) clearly has gradient 0, so we draw the line y = 0 below this part •finally, the parabolic portion on the right will have gradient 2x - 8, so we draw a line with gradient 2 Note that the gradient is undefined when x = 0, so the derived function graph has no value at x = 0. The empty (or open) circles at x = 0 show that 0 is excluded from the domain of f(x). Take a look at some applets that draw the graph of the derived function for various functions. Each applet shows how the gradient changes as you move along a graph. These applets are linked to from the Theta Mathematics links page at www.mathematics.co.nz. DATA 6/13/11 1:31 AM 348 2.7 Calculus methods 9 A train passes a signal at a speed of 12 m/s. The train’s acceleration t seconds after passing the signal is (4 - 2t) m/s2, until it comes to rest. a For how many seconds after passing the signal does the train continue to gain speed? b Find, in terms of t, an expression for the speed, v m/s, of the train. c What is the greatest speed attained by the train after it has passed the signal? d How long after passing the signal does the train take to stop? e How far past the signal did the train travel? down does the aircraft take to reach normal taxiing speed? ly a If the speed of the spacecraft was 10 m/s at the moment the engines were fired, find an expression for the speed, v m/s, of the spacecraft at time t. b In terms of the spacecraft, what 2 information would be given by v dt ? D ra ft on 23 - co py rig ht Pe ar s on 7 At a certain moment on its journey, the rocket engines of a spacecraft were fired. Its acceleration, a m/s2, t seconds after that moment is given by a = 3t - 1. ∫0 8 A machine is driving piles for a wharf in a river estuary. It does this by lifting a heavy weight 4 m directly above the pile, and then releasing the weight onto the pile. The impact drives the pile into the riverbed. The acceleration of the weight is 4.9 m s-2. a What is the initial velocity of the weight? b How long does the weight take to reach the pile? (Hint: find an expression involving distance s, and then substitute s = 4.) c Find the velocity of the weight when it hits the pile. 9781442549487_CH-23.indd 348 10 A boat is travelling at a constant speed of 12 m s-1 towards a marina. The speed limit in the marina is 2 m s-1 so the boat decelerates when it passes a buoy. The acceleration of the boat t seconds after passing the buoy is given by the rule: a= −t . 5 a How long does the boat take to show down to the speed limit? b Calculate the distance travelled by the boat after passing the buoy until it reaches the speed limit. 6/13/11 3:25 AM 384 2.12 Probability methods 7 This table gives information about simplified weather forecasts over a 90-day period in a region of New Zealand. Calculate the probability that the weather forecast was correct on any given day. Forecast Dry Actual weather Dry Wet Total Wet Total 49 8 57 5 28 33 54 36 90 Risk and relative risk The risk that a New Zealander will currently have a diagnosis of Type 2 diabetes (as at July 2010) was about 4.1%. That information is not particularly useful overall unless it is considered together with risk factors. These risk factors are a mixture of lifestyle and other factors, and sometimes they are linked and not independent. py ARTER - co ST rig ht Pe ar s on Risk can be thought of as probability. The term ‘risk’ is usually used in connection with events that have unpleasant consequences (e.g. death, serious disease, etc.) and, although some of the events may be subject to uncertainty, sometimes there are factors relating to exposure or otherwise that can either reduce the risk or make it worse. For example, the risk of injury or death from a serious road crash is reduced for someone who wears a safety-belt, and is increased for those who drive after drinking alcohol or who use a cell phone while driving. Whether a crash occurs or not is still uncertain (subject to some randomness or unpredictability) but some of the factors associated with driving can either increase or decrease the probability that the crash occurs. on Overweight ly At increased risk Normal weight Older than 40 years old Younger than 40 years old Diabetes runs in family Physically active ra ft 25 Reduced risk D Live in the North Island _ Maori/Pacific Islander 1 Discuss which risk factors above are able to be influenced by an individual. 2 aWhich risk factor above is most associated with living in the North Island? Explain why. bWould it help someone who wanted to avoid diabetes to move to the South Island? 3 The risk of an overweight person developing Type 2 diabetes is 10%. Complete this sentence: ‘Compared to the general population, a person who is overweight is about times more likely to develop Type 2 diabetes.’ (Source: http://www.diabetes.org.nz/resources/DHB_figures) 9781442549487_CH-25.indd 384 6/13/11 4:03 AM 25 Further probability 385 9 Relative risk Here we consider relative risk – that is, the likelihood of the event when given factors are taken into account. The relative risk of an event for a particular group or to a certain kind of exposure describes how likely this risk is compared to the risk of the same event for another group or to a different kind of exposure. Examples 1The relative risk of a smoker developing lung cancer compared to a non-smoker developing lung cancer – here the two groups (smokers and non-smokers) are complementary. 2The relative risk of drowning in a swimming pool compared to drowning in any body of water – here the first group is those who swim in a pool, and this is a subset of the second group, which is those who swim anywhere, including a pool. on How do we calculate relative risk? ar s Relative risk of an event for group A compared to the risk of the same event for group B is the ratio of the probability of the event for group A to the probability of the event for group B. ht Pe Example This table shows data for a study of deaths from lung cancer versus other causes of death in the United States. The table also shows whether the person was a smoker or not. rig (Source: http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Epidemiology.html) Non-smoker 397 Other causes 6919 4614 Total 7316 4651 ly - co 37 py Smoker Lung cancer 397 = 5.43%. 7316 Risk of a non-smoker dying of lung cancer: 37 = 0.80%. 4651 Based on this study, the relative risk of dying of lung cancer for a smoker compared to a non-smoker dying of lung cancer, is 5.43 = 6.8. 0.80 25 D ra ft on Risk of a smoker dying of lung cancer: That is, a smoker is almost seven times more likely to die of lung cancer than a non-smoker. T I P Relative risk is not a probability. Relative risk can have values greater than 1 (e.g. relative risk of cancer for a smoker compared to cancer for a non-smoker) or less than 1 (e.g. risk of head injury for a cyclist who wears a crash helmet compared to risk of head injury for all cyclists). 9781442549487_CH-25.indd 385 6/13/11 4:03 AM 386 2.12 Probability methods EXERCISE 25.03 1 Two airlines flew the Auckland to Christchurch route in December 2010 and January 2011. This table shows the number of on-time flights and the number of delayed flights over that period. Air New Zealand Jetstar Total 105 56 161 On-time 947 199 1146 1052 255 1307 Total 4 The table gives data regarding seat-belt use and blood alcohol concentration (BAC) for car and van drivers killed between 2005 and 2007. BAC is measured in mg of alcohol per 100 mL of blood. on Delayed Calculate the relative risk of being delayed on this route when flying Jetstar compared to being delayed when flying Air New Zealand. Total 87 19 63 26 113 ly 44 50 on Have not had lessons 7 Pe Calculate the relative risk of failing the practical driving test if an applicant has not had lessons from a professional driving instructor compared to failing the test if the applicant has had lessons from a professional driving instructor. D 43 ra ft 25 Had lessons Total - Pass test Fail test 3 The risk of a car being stopped for any reason by the police when the driver is using a mobile phone is 0.048. The risk of a car being stopped for any reason when the driver is not using a mobile phone is 0.000 32. What is the relative risk of a car being stopped for any reason when the driver is using a mobile phone compared to the car being stopped when the driver is not using a mobile phone? 9781442549487_CH-25.indd 386 Wearing a Not wearing seat-belt a seat belt ht co py 2 A testing centre keeps statistics on whether applicants for a driver licence pass the practical test. The centre has also recorded whether applicants have had lessons from a professional driving instructor. Car and van drivers killed 2005–07 Below the 80 mg per 100 mL of blood limit 87% 13% Above the 80 mg per 100 mL of blood limit 54% 46% rig ar s (Source: http://www.flightstats.com) (Source: www.transport.govt.nz/research/.../Alcohol-DrugsCrash-Factsheet.pdf) What is the relative risk for a driver not wearing a seat-belt and who was over the legal BAC limit of 80 mg per 100 mL compared to the driver who was not wearing a seat-belt and was below the same limit? 5 This table shows data for flight delays and numbers of flights operated from Auckland to Brisbane over a two-month period. Total number On-time Delayed of flights Air New Zealand China Airlines Emirates Pacific Blue Qantas 95 28 123 4 42 19 77 1 18 5 28 5 60 24 105 (Source: http://www.flightstats.com) 6/13/11 4:03 AM 25 Further probability co 30+ years 20–29 years 15–19 years March 8 April 9 May 11 June 14 July 13 August 13 September 12 October 12 ar s November December 8 What is the relative risk of experiencing a wet day in Wellington in the second half of the year (July–December: 184 days altogether) compared to the first half of the year (January–June: 181 days altogether)? Pe 10 8 The graph shows the relative risk of fatal crash by blood alcohol level for different age groups of driver. 1 3 30 2.9 8.7 50 5.8 17.5 30.3 200 80 16.5 50.2 86.6 160 age 20–29 140 age 30+ 5.3 Relative risk of fatal crash by blood alcohol level 15 Current New Zealand BAC limit ly on ra ft a How does the table show that the calculation of risk is made in relation to that of a sober driver aged 30+ years? b Estimate the relative risk, at all age levels, for a driver with a BAC of 50 compared to a driver with a BAC of 30. 7 A ‘wet day’ is defined as one that has at least 1.0 mm of rain. This table gives the mean number of wet days in Wellington for each month. 9781442549487_CH-25.indd 387 120 100 25 80 60 40 20 0 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 BAC (mg/100 mL) ( Source: www.transport.govt.nz/research/.../Alcohol-DrugsCrash-Factsheet.pdf) age 15–19 180 D 7 0 (Source: MOT Crash Fact Sheet 2008) February py Age of driver 7 - BAC January ht 6 This table shows calculations of relative risk for being involved in a fatal road crash by both age and blood alcohol concentration (BAC). BAC is measured in mg of alcohol per 100 mL of blood. Wet days rig Increase in risk Month on a Based on the data for this two-month period, calculate these relative risks for being delayed on a flight from Auckland to Brisbane: i flying Qantas compared to Pacific Blue ii flying Emirates compared to Air New Zealand iii flying Pacific Blue compared to China Airlines iv flying Air New Zealand compared to any other airline. b Which airline has the lowest relative risk of delay on this route compared to any other? c For which airline is the data most unreliable? Explain. 387 a At what BAC is a teenage driver ten times more likely to have a fatal road crash than if the driver were completely sober? b A driver aged 40 is almost twice the legal BAC, which is 80 mg per 100 mL of blood at the time of writing. How many more times likely is this driver to have a fatal road crash than if their BAC were just on the legal limit? 6/13/11 4:03 AM 26 The normal distribution 419 2 Applications ar s Pe ht First, enter the mean (m) and the standard deviation (s). These values are used to generate a scale for the normal distribution with those parameters. Note that the default values (0, 1) give the standard normal curve. on The e-book version of this textbook comes with the application ‘Pearson Normal Probability Calculator’, which can calculate any normal probability, given the mean and standard deviation. py rig Then choose one of these three options: co 1 P(X < a) on ly - 2 P(X > a) ra ft 3 P(b < X < c). 26 D Enter the value of a, or values of b and c, then click on ‘Close’, and the application draws a normal curve and uses colour to display the area that corresponds to the required probability. 9781442549487_CH-26.indd 419 6/13/11 4:17 AM 421 26.06 - EXERCISE co py rig ht Pe ar s on 26 The normal distribution TECH ra ft on ly 1 X has a normal distribution with a mean of 36 and a standard deviation of 8. Use appropriate technology to calculate these probabilities. a P(X < 39) b P(X < 27.5) c P(X > 33) d P(X > 41.74) e P(39 < X < 51) f P(33.6 < X < 39.2) g P(28.9 < X < 43.5) 26 D 2 X has a normal distribution with a mean of 19 and a standard deviation of 1.73. Match each probability below with the correct spreadsheet formula (A–C) from the given list. a P(X < 21) b P(X > 21) (A) =NORMDIST(19,21,1.73,TRUE) (B) =NORMDIST(21,19,1.73,TRUE) (C) =1-NORMDIST(21,19,1.73,TRUE) 3 X has a normal distribution with a mean of 19 and a standard deviation of 1.73. Match each probability below with the correct spreadsheet formula (A–E) from the given list. a P(18.9 < X < 23.4) b P(X < 18.9 or X > 23.4) (A) =NORMDIST(23.4,19,1.73,TRUE)+NORMDIST(18.9,19,1.73,TRUE) (B) =NORMDIST(18.9,19,1.73,TRUE)+1-NORMDIST(23.4,19,1.73,TRUE) (C) =NORMDIST(23.4,19,1.73,TRUE)+NORMDIST(21,19,1.73,TRUE)-1 9781442549487_CH-26.indd 421 6/13/11 4:18 AM 430 2.12 Probability methods The area to the right of k is 0.325. Therefore the area to the left is 1 - 0.325 = 0.675. Because the CAS calculator works with left-hand area, we enter 0.675 as the ‘area’. That is, P(X > 215.176) = 0.325. DATA ar s on The steps for the Casio ClassPad 300 are explained in the CAS information sheet in the Theta Mathematics Teaching Resource, and here is a hyperlink if you are using the e-book version of this textbook. ht rig py ra ft First, enter the mean (m) and the standard deviation (s). These values are used to generate a scale for the normal distribution with those parameters. D 26 on ly - co The e-book version of this textbook comes with the application ‘Pearson Normal Probability Calculator’, which can calculate any value on a normal distribution scale, given the mean, standard deviation, and probability of being either greater than or less than the unknown value. Pe 2 Applications Then choose one of these two options: 1 P(X < a) = k 2 P(X > a) = k 9781442549487_CH-26.indd 430 6/13/11 4:18 AM 432 2.12 Probability methods - co py rig ht Pe ar s on The screenshot shows the result of an ‘inverse normal’ calculation for a normal distribution with a mean of 212 and a standard deviation of 7. ly b ra ft 1 Each diagram shows a normal curve with a mean of 10 and a standard deviation of 3, and an associated probability. Match each diagram with the correct spreadsheet formula (A–G) that would be used to calculate the value(s) on the horizontal axis. a TECH 0.77 D 26 26.10 on EXERCISE 10 k c 0.85 j = 10 l (A) =NORMINV(0.85,10,3) (B) =NORMINV(0.38,10,3) 9781442549487_CH-26.indd 432 (C) =NORMINV(0.77,10,3) (D) =NORMINV(0.31,10,3) (E) =NORMINV(0.15,10,3) 0.38 = 10 (F) =NORMINV(0.23,10,3) (G) =NORMINV(0.89,10,3) 6/13/11 4:18 AM 27 Simulation methods on dNow recalculate the spreadsheet at least 50 times. Write the number of purchases needed to get all five colours each time. eExplain how you would estimate the ‘average’ number of purchases needed to qualify for a free car-wash. fInvestigate to find out the number of purchases needed if a sixth colour, equally likely with the others, were added. ht Pe 4 The World Series The World Series is the name given to the final stages of the annual Major League Baseball Championships in North America. ar s 443 co py rig The winner of the World Series is the first team to record four victories, which means the series is a ‘best of seven’ event. In this simulation, assume that each team is equally likely to win an individual game. D ra ft on ly - The spreadsheet extract shows the result of simulating 20 different years of World Series games between team A and team B. This simulation shows which team wins each game, and also shows the cumulative number of wins at each stage. No more games are needed after scores of 4–0, 4–1, 4–2, 4–3, 0–4, 1–4, 2–4 and 3–4. This is shown, in some cases, by blank cells in the columns for games 5 and 6. 9781442549487_CH-27.indd 443 27 6/13/11 4:47 AM 460 2.14 Systems of equations 28 Simultaneous equations Mathematics and Statistics in the New Zealand Curriculum Mathematics: Patterns and relationships Level 7 • M7-8 Form and use pairs of simultaneous equations Pe ht A linear equation can be represented on a graph by a straight line. co py rig Simultaneous equations are equations that apply at the same time. Here we consider a pair of equations in two unknowns, x and y. The solution will be the numbers x and y that satisfy both equations. Note: if we have two unknowns, we need two equations in order to solve for x and y. We start with ‘linear’ equations in x and y. There are several methods that can be used to solve these. ar s on Achievement Standard Mathematics and Statistics 2.14 – Apply systems of equations in solving problems Finding intersections by drawing lines ra ft on ly - Example Draw a graph to solve these simultaneous equations. (1) x + y = 5 (2) y = 2x − 1 Answer y 5 D y = 2x – 1 3 The graphs intersect at the point (2, 3). x+y=5 Hence the solution is x = 2 and y = 3. 28 –1 EXERCISE 2 5 x 28.01 Find the point of intersection of these pairs of lines by drawing graphs. 1 y = 3x + 1 y = 2x + 2 3 2x + y = 4 y = x − 5 5 y + 3 = x 3x + y = 1 7 2x + y = 0 y = x − 3 2 y = 3 − x y = x + 7 4 2x − y = 3 y = 5x 6 2x = y − 5 x + y = 2 8 y = x + 2 2y = 5x − 2 9781442549487_CH-28.indd 460 6/13/11 5:22 AM 28 Simultaneous equations 16 A business uses different depreciation rates for different items of equipment. A computer decreases in value by 30% per year, and a photocopier decreases in value by 20% per year. The business buys one computer and one photocopier for a total of $10 000. At the end of the year, they are valued at $7600 altogether. How much did the business pay for each machine? 17 An internet service provider offers users a choice of two monthly rate plans. on ar s py - ly 40 D y = 2x – 50 on 30 co A Hours on-line ra ft Cost per month ($) B Pe Suppose x is the number of hours on-line, and y is the monthly charge. This graph (not drawn to scale) is provided to users, and shows the equations for Plan B. y = 30 18 A school uses two minibuses to take a group of students on a field trip. • If one student moved from the first minibus to the second, the two minibuses would have the same number of students. • However, if a student moved from the second minibus to the first, the first minibus would have twice as many students as the second minibus. a Use this information to write a pair of simultaneous equations. b How many students are in the group altogether? ht Each hour costs $1.50. The first 40 (or fewer) hours cost $30. Hours over 40 cost $2 each. a Show that both of the equations for Plan B give the same result for a user who expects to be connected for exactly 40 hours. b Write the equation for Plan A. c Solve some simultaneous equations to find the range of values for which Plan B is a better deal than Plan A. Show your working, and explain what you are working out at each step. rig Plan A Plan B The great picnic puzzle PUZZLE This puzzle was originally published in 1914 in Sam Loyd’s Cyclopedia of 5000 Puzzles, Tricks and Conundrums with Answers. When they started off on the great annual picnic, every wagon in town was pressed into service. Half-way to the picnic ground, 10 wagons broke down, so it was necessary for each of the remaining wagons to carry one more person. When they started for home, it was discovered that 15 more wagons were out of commission so, on the return trip, there were three persons more in each wagon than when they started out in the morning. Now, who can tell how many people attended the great annual picnic? 9781442549487_CH-28.indd 467 467 28 6/13/11 5:23 AM Uncorrected Sample Pages Theta Mathematics has been completely updated to reflect the current requirements of Mathematics and Statistics in the New Zealand Curriculum. In order to provide teachers and students with a comprehensive package that covers all thirteen Achievement Standards, Theta Mathematics is complemented by Theta Dimensions. This edition follows in the tradition of all David Barton’s resources and contains: • material that addresses the requirements of the front end of the New Zealand Curriculum, including the Vision, Key Competencies, Values and Cross and Bicultural references • concise theory notes written with students’ needs in mind • comprehensive worked examples that are well set out • plenty of questions in context • graded exercises to practise skills and build solid foundations • questions that require understanding and explanation, and some extended working • investigations and puzzles, many new, to motivate students and stimulate thinking • references to technology throughout, including animations, spreadsheet work, CAS calculators, and websites that are linked from www.mathematics.co.nz • complete answers. Also available THETA MATHEMATICS WORKBOOK • Includes the topics that lead on to either a Statistics course or a Calculus course in Year 13 • Includes the topics that are currently assessed externally. THETA DIMENSIONS and THETA DIMENSIONS WORKBOOK • Includes the internally assessed topics that lead into a Statistics course in Year 13. ISBN 978-1-4425-4948-7 9 9781442549487_3 climbers_COV.indd 1 781442 549487 MATHEMATICS The chapters for each Achievement Standard are colour-coded to make them easy to find, and liberal use of colour throughout the book makes it easy and interesting to use. Helpful tags on the edge of each page enable students to navigate between the answer section and the related exercises. Theta Mathematics 2.1 Co-ordinate geometry 2.2 Graphical models 2.4 Trigonometric relationships 2.6 Algebraic methods 2.7 Calculus methods 2.12 Probability methods 2.13 Simulation 2.14 Systems of equations
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