Let's solve each problem step by step using the
formula for the circumference of a circle:
$$
C = 2\pi r \quad \text{or} \quad C = \pi d
$$
Where:
- $ C $ is the circumference,
- $ r $ is the radius,
- $ d $ is the diameter,
- $ \pi = 3.14 $ (as given).
We’ll use $ C = 2\pi r $ when the
radius is given, and $ C = \pi d $ when the
diameter is given.
---
Problem 1
- Radius $ r = 17 $ yd
$$
C = 2 \times 3.14 \times 17 = 6.28 \times 17 = 106.76 \text{ yd}
$$
✔ Answer: 106.76 yd
---
Problem 2
- Radius $ r = 13 $ cm
$$
C = 2 \times 3.14 \times 13 = 6.28 \times 13 = 81.64 \text{ cm}
$$
✔ Answer: 81.64 cm
---
Problem 3
- Radius $ r = 10 $ ft
$$
C = 2 \times 3.14 \times 10 = 6.28 \times 10 = 62.8 \text{ ft}
$$
✔ Answer: 62.8 ft
---
Problem 4
- Diameter $ d = 18 $ ft → So radius $ r = 9 $ ft
Use $ C = \pi d $:
$$
C = 3.14 \times 18 = 56.52 \text{ ft}
$$
✔ Answer: 56.52 ft
---
Problem 5
- Radius $ r = 38.5 $ ft
$$
C = 2 \times 3.14 \times 38.5 = 6.28 \times 38.5 = 241.78 \text{ ft}
$$
✔ Answer: 241.78 ft
---
Problem 6
- Diameter $ d = 66 $ m
$$
C = 3.14 \times 66 = 207.24 \text{ m}
$$
✔ Answer: 207.24 m
---
Problem 7
- Radius $ r = 0.5 $ m
$$
C = 2 \times 3.14 \times 0.5 = 6.28 \times 0.5 = 3.14 \text{ m}
$$
✔ Answer: 3.14 m
---
Problem 8
- Diameter $ d = 44.4 $ ft
$$
C = 3.14 \times 44.4 = 139.236 \text{ ft}
$$
✔ Answer: 139.24 ft (rounded to two decimal places)
---
✔ Final Answers:
1.
106.76 yd
2.
81.64 cm
3.
62.8 ft
4.
56.52 ft
5.
241.78 ft
6.
207.24 m
7.
3.14 m
8.
139.24 ft
Let me know if you'd like this formatted as a printable answer sheet!
Parent Tip: Review the logic above to help your child master the concept of area of a circle worksheet.
