Let’s solve each problem one by one.
We’re given:
- Area formula: A = πr²
- Circumference formula: C = πd (or C = 2πr, since d = 2r)
- Use π = 3.14
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Problem 1:
Radius r = 3 in. → Find Area (A)
A = 3.14 × (3)² = 3.14 × 9 =
28.26 in²
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Problem 2:
Diameter d = 7 yd. → Find Circumference (C)
C = 3.14 × 7 =
21.98 yd
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Problem 3:
Radius r = 5 m. → Find Area (A)
A = 3.14 × (5)² = 3.14 × 25 =
78.5 m²
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Problem 4:
Diameter d = 10 m. → Find Circumference (C)
C = 3.14 × 10 =
31.4 m
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Problem 5:
Radius r = 9 ft. → Find Circumference (C)
First, find diameter: d = 2 × 9 = 18 ft
C = 3.14 × 18 =
56.52 ft
*(Alternatively, C = 2πr = 2 × 3.14 × 9 = same result)*
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Problem 6:
Diameter d = 8 cm. → Find Circumference (C)
C = 3.14 × 8 =
25.12 cm
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Problem 7:
Radius r = 13 mm. → Find Circumference (C)
Diameter d = 2 × 13 = 26 mm
C = 3.14 × 26 =
81.64 mm
*(Or C = 2 × 3.14 × 13 = same)*
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Problem 8:
Radius r = 16 mi. → Find Area (A)
A = 3.14 × (16)² = 3.14 × 256 =
803.84 mi²
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All calculations verified.
Final Answer:
1. A = 28.26 in²
2. C = 21.98 yd
3. A = 78.5 m²
4. C = 31.4 m
5. C = 56.52 ft
6. C = 25.12 cm
7. C = 81.64 mm
8. A = 803.84 mi²
Parent Tip: Review the logic above to help your child master the concept of circumference and area worksheet 1.
