Name
LESSON
Date
Class
Practice C
10-5 Area of Circles
1. Find the area of the circle by using a formula. Use 3.14 as an
estimate for . Then use an estimate to check whether your
answer is reasonable.
Find the area of each circle to the nearest tenth. Use 3.14 as an
estimate for .
2.
3.
9.5 in.
12 cm
5.
4.
7 yd
6.
7.
1.4 in.
2.5 ft
7.6 cm
Given the radius or diameter, find the circumference and area of
each circle to the nearest tenth. Use 3.14 as an estimate for .
8. r 4 in.
9. d 14 cm
10. d 26 ft
Given the area, find the radius of each circle. Use 3.14 as an estimate for .
11. A 200.96 m2
12. A 12.56 in2
13. A 314 yd2
14. A playground area is circular with a diameter of 32 feet.
What is the area of the playground? Use 3.14 as an
estimate for and round your answer to the nearest tenth.
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
39
Holt Mathematics
Practice A
LESSON
10-5 Area of Circles
Practice B
LESSON
10-5 Area of Circles
1. Find the area of the circle by using a formula. Use 3.14 as an
estimate for . Then use an estimate to check whether your
answer is reasonable.
1. Find the area of the circle by using a formula. Use 3.14 as an
estimate for . Then use an estimate to check whether your
answer is reasonable.
Possible answer: 28.26 units2; estimate: 28 units2
Possible answer: 12.56 units2; estimate: 13 units2
Find the area of each circle to the nearest tenth. Use 3.14 as an estimate for .
Cross out each number in the box that matches an area.
Find the area of each circle to the nearest tenth. Use 3.14 as an
estimate for .
2.
19.6
254.3
153.9
28.3
50.2
78.5
22.0
260.0
3.1 379.9
171.9
72.3
2.
3.
6m
4.
8 ft
7 yd
176.6
3.
113.0 m2
4.
153.9 yd2
50.2 ft2
9 yd
4 in.
14 m
5.
6.
50.2 in2
153.9 m2
5.
7.
11 in.
5 cm
3 mm
254.3 yd2
6.
19.6 cm2
7.
10 in.
7.4 cm
379.9 in2
8.
2 cm
28.3 mm2
9.
10.
7.2 yd
10 in.
13 cm
3.1 cm2
171.9 cm2
8.
78.5 in2
9.
78.5 in2
10.
2.5 ft
22 mm
162.8 yd2
132.7 cm2
6m
11. A Susan B. Anthony dollar coin has a diameter of
26.50 millimeters. What is the area of the coin to
the nearest hundredth? Use 3.14 as an estimate for .
379.9 mm
2
19.6 ft
2
28.3 m
11. Find the area of the shaded region of the
circle. Use 3.14 as an estimate for .
Round your answer to the nearest tenth.
551.27 mm2
2
12. A tablecloth for a round table has a radius of 21 inches.
22
What is the area of the tablecloth? Use 7 as an
estimate for .
12 in.
1,386 in2
56.5 in2
37
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
Holt Mathematics
38
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
Holt Mathematics
Practice C
LESSON
10-5 Area of Circles
Review for Mastery
LESSON
10-5 Area of Circles
1. Find the area of the circle by using a formula. Use 3.14 as an
estimate for . Then use an estimate to check whether your
answer is reasonable.
The formula A r 2 is used to find the area of a circle. Since the
value of is about 3.14, you can use the formula A 3.14 r r to
estimate the area of a circle. Remember that area is expressed in
square units.
The radius of the circle is 4 in.
Possible answer: 78.5 units2; estimate: 78 units2
A 3.14 r r
Find the area of each circle to the nearest tenth. Use 3.14 as an
estimate for .
2.
3.
113.0 cm2
A 50.24
The area of the circle is 50.2 in2
to the nearest tenth.
7 yd
283.4 in2
5.
A 3.14 4 4
4.
9.5 in.
12 cm
4 in.
Find the area of each circle to the nearest tenth. Use 3.14 as an estimate for .
38.5 yd2
6.
1.
7.
2.
9 cm
10 mm
1.4 in.
2.5 ft
7.6 cm
6.2 in2
45.3 cm2
19.6 ft2
The radius is
9
cm.
The diameter is 10 mm.
A r 2
Given the radius or diameter, find the circumference and area of
each circle to the nearest tenth. Use 3.14 as an estimate for .
8. r 4 in.
9. d 14 cm
C 25.1 in.
A 50.2 in
2
A 153.9 cm
A
10. d 26 ft
C 44.0 cm
A 530.7 ft
r8m
12. A 12.56 in2
3.
r 2 in.
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All rights reserved.
39
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
r 10 yd
379.9 yd2
Holt Mathematics
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
133
5
78.5
A 3.14 cm2 to
A
mm.
5
78.5
The area is
the nearest tenth.
m2 to
5.
3m
12 ft
28.3 m2
113.0 ft2
6. What is the area of a circle with radius 13 yd?
Round your answer to the nearest tenth.
803.8 ft2
5
A r 2
4.
11 yd
13. A 314 yd2
14. A playground area is circular with a diameter of 32 feet.
What is the area of the playground? Use 3.14 as an
estimate for and round your answer to the nearest tenth.
9
2
Given the area, find the radius of each circle. Use 3.14 as an estimate for .
11. A 200.96 m2
254.3
The area is
the nearest tenth.
C 81.6 ft
2
9
254.34
A 3.14 The radius is
40
530.7 yd2
Holt Mathematics
Holt Mathematics