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Name
Gircumference
R to.11
Finding the circumference of a circle:
Find the circumference.
Diameter
:
Find the circumference.
Bm
Radius
Since you know the diameter, use the
formula C: nd.
:
12 m
Since you know the radius, use the
formula C :2nr.
C:rd
C:3.14x8
: 25.12 m
C:2rr
C:2XnX12
:2x3.14x12
: 6.28 x 12
: 75.3G
So, the circumference is 25.12 m.
So, the circumference is 75.36 m.
Finding the diameter or radius of a circle:
Find the diameter.
Find the radius.
:
Circumference 65.g4 m
Circumference:
Use the formula C
65.94
:
:
nd.
40.92ft
Use the formula C
:
2nr.
40.82:2xnxr
trd
65.94 :3.14d
65.94 _ 3.14 q
-g1T
- 3i4 ^,
40.82:2x3.14xr
40.82
21 :d
:
6.28
r
_ 6.28
6.28 - 6E I-
40.82
So, the diameter is 21 m.
6.5:r
So, the radius is 6.5 ft.
Find each circumference. Use
1.
?
or 3.14 for n.
2.
(o
O
c
i
.9
(g
o
J
!
rll
c
Find the missing measurements for each circle. Round
to the nearest hundredth.
4. C:
39.25 ft,
d126
5. C:63.3024m,
rUse with Lesson 1o-11.
6. r:
C-
5.95 yd,
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Name
Circumference
Find each circumference. Use 3.14 or
P 10.1{
I
tor n.
Find the missing measurement for each circle. Round
to the nearest hundredth,
3. C :
60.288 cm,
d:
4. C:11.304
(n,r:
5. Estimation cDs have a diameter of about 5 in. Estimate
the circumference of a CD.
Test Prep
6. Angela baked an appre pie that had a radius of 6 in. she wants
to cut the pie into eight equal srices. How wide at the
outer end
will each piece of pie be?
A.
5.2 in.
B. 4.7 in.
C. 4.4 in.
D. 4.2 in.
7. Writing in Math Based
on the diagram, is it
correct to say that the smaller circle has one
half the circumference of the larger? Why?
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126
Use with Lesson 1o-11.
Name
Gircumference
PS
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sports Measurements The measurements of some sports
equipment are listed in the table.
Sports Measurements
Baseball
circumference of g in.
Basketball
circumference of 30 in.
Basketball hoop
diameter of 18 in.
Bowling ball
circumference of 27 in.
1. What is the circumference of a basketball hoop?
2.
To the nearest tenth of an inch, what is the diameter
of a bowling ball?
3. stephen
said the radius of a baseball is about 3 in. ls he correct?
lf not, give the correct answer.
The First Ferris wheel rhe first Ferris wheel was built for the
world's columbian Exposition that was held in chicago in 1gg3. lt
was designed by a bridge builder named George rerrl and had a
diameter of 250 ft.
4.
How far would you travel sitting in a Ferris wheel car
that went around the complete circle twice?
5.
lf you were in a Ferris wheel car that had traveled
1 complete circle, and your friend was in a car that
had traveled 1* circles, how much farther would
your friend hav'e traveled?
(o
6. writing
in Math Explain how you would use mental math to find an
estimate of the circumference of a circle that has a radius of 10 mm.
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Use with Lesson 1o-1't.
Name
Possible or
Impossible?
1.
ls it possible for a circle with a 4 in. diameter to fit inside a circle
with a 15 in. circumference? Explain your answer.
2,
ls it possible for a circle with a radius of 2fl to contain a circre
with an 11 ft circumference? Explain your answer.
"=^:"J$ll
3. Asha has a bracelet with a 3 in. diameter. The circumference of
her wrist is 7 in. Do you think Asha will be able to wear the
bracelet? Explain your answer.
4.
The circumference of Priscilla's head is 21 in. She has a
necklace that has a radius of 5 in. that must slip over her
head. ls it possible for Priscilla to wear the necklace?
Explain your answer.
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5.
c
The circumference of Paul's head is 23 in. He has a hat that has
a 5 in. diameter. Do you think Paul will be able to wear his hat?
Explain your answer.
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1.\a
Circumference
Find each
ci
rcumferenc e. lJso B.j 4 ot
t f-2,
P IO.l t
+
(.Y\
Y)
Circumference
Finding the circumtorcnce of a circle:
2.
Find the circumterence.
Diameter
ei.ooft
Radius
the
Since you know the diametei use
75.36 cm
10.2 cm
Find the circumference.
=8m
4. c:11.s04m,r=
rd.
formulac =
i.g m
So, the circumfe.ence
c=2nr
c=2xTx12
=2x3.14x12
s.2
Circumference
in.
7. Writing in Mdh
@a.z
in
C.4.4in
12
= 75.36
Finding the diametgr or Edius of a circle:
Find the diameter
Find the radius.
= 65.94 m
Circumference
Use th€ formula C = Td.
Angela baked an apple pie that had a radjus of 6 in. She wants
to cut the pie into eight equal stices. How wide at the outer
end
will each piece of pie be?
A.
x
= 6.28
m.
is 2s.12
So, the circumference is 75.36 m
Test Prep
6.
12 m
tomulao = 2rr.
5. Estimalion
CDs have a diameter ofabout S in. Estimate
the circumference of a CD.
=
Since yod know the radius, use the
C=rd
c=a.14x8
:2s.12m
Find the missing measuEment for each circle. Round to the
nearest hundEdth.
3. c:60.28Bcm,d=
n to.t I
tot ft.
65.94
:
zd
65.94
m-mo3.1a
O.4.2in
21
40.82
ft
2rr
40.82=2xT\t
65.94 = 3.14d
Based on the diagrm, is it
-
Use the formula C =
40.82=2x3.14xr
,
40.82
=d
:
r
6.28
E#-#,
So, the diameter is 21 m.
6.5:/
So, the radius is 6.5 ft.
Find oach circumforence. Use
+
3.
G;1
i
€
6
3
i\
l-a;^)
*Y'
\:
r.
or 3.14 for
Mo
77,872cm
Find ihe missing measurements for each
circle. Round to ths nearest hundredth.
4, C =
126
39.25
ft,
S.
C
"_1?€ft
126
u"."tnr"".onro,rr
. 63.3024
m.
_i0.08m
-
6. , = S.95 vd.
_Cz.ilzvo
u""*mu""onro.,.
Possible or lmpossible?
E
to.l I
BEASOX|f,C
ls it possible for a circle with a 4 in. diameter to fit inside
a circle
wiih a 15 in. circumference? Explain vouranswer
Circumference
PS to.t
I
Sports Measutementg The measurements ol some
sports
equipment are listed in the tabte.
Sports Measurements
2.
ls it possible for a circle with a radius ot 2 ft to contain
a ciicle
with an 1 1 Jt circumference? Explain your answer
The
1. What
circumference of
Basketball
circumference of 30 in
Asha has a bracelet with a 3 in. diameter Tire circumference of
her wrist is 7 in. Do you think Asha will be able
bracelet? Explain your answer
Basketball hoop
diameter of 18 in.
circumterence of 27 in.
is the
circumference.
4.
To
3,
Stephen said the radius of a baseball is about g
in. ls he
lf not, give the corect answen
ihe near€st tenth of an inch, what
No; Sincc 3 x 2
and the dlameter ot her nea
5.
than 16 in.
126
126
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Use with Chapter 10, Lesson 11
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How far woutd you tGvet siflino in a Fer
tn",*"nt".,,ii',"1o-."o;;;'"',','#'"u.]i:t"in"u'""' 11570
lf you were in a Ferris wbeel @r that had traveled
1 complele circl€, and your fdend was in
a car that
had tGveted
circtes, how much fadhr€r
-"
your friend havi traved
l;
No: Thg hat's circumference is less
tr=18.9.
@
World's Columbian Exposition'o,
that w6 h6td in Chicago tn j893. lt
was dGigned by a bridge bujtd6. named
George F6rls ed had a
diamater of 250 ft.
Yesj.@sroin
The circumference of paul,s head is 23 in. He has a hat that
has
a 5 in_ diamete[ Do you think paul will be able
to wear his hat?
Explain your answer
8.6|n.
cortrt?
-.
The.Firl! Feris Wheet
4.
5,
x
is the diamoter
theoiameterisffinot
infi
The circumference of priscilla,s head is 21 in. She has
a
ntrkJace that has a radius of 5 in_ that must slip over her
head. ls it possible for priscilla to wear the necklace?
Explain your answer
56,5i1in.
circumfe€nce of a basketball hoop?
2.
to,"u,tf,u
Y9e; The bracelet is g.4Z
in
Bowlinq batl
of a bowling ball?
3.
I
Baseball
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woulo
o
c
i
ft
F
G
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@2.5
c
ft
o
a
6
6. Writlng ln Mdh
Explain how you would use mmtat malh to frnd an
Gflmate ot the circuml€renm of a circle thal hs a raa,us
ot tO mm.
SaFplc anawer:"Flnrtyou would double thc
flnd
3Io tlnd an csfimato for tho
20mm x 3o60mm.
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