Let's solve the
Circles - Circumference worksheet step by step.
We are asked to find the
circumference of each circle given either the
radius or
diameter. The formula for the circumference $ C $ of a circle is:
$$
C = \pi \times d \quad \text{or} \quad C = 2\pi \times r
$$
Where:
- $ d $ is the diameter,
- $ r $ is the radius,
- $ \pi \approx 3.14 $ (we'll use this approximation unless otherwise specified).
---
Problem 1: Diameter = 36 yd
$$
C = \pi \times d = 3.14 \times 36 = 113.04 \text{ yd}
$$
✔ Answer: 113.04 yd
---
Problem 2: Radius = 12 ft
Use $ C = 2\pi r $:
$$
C = 2 \times 3.14 \times 12 = 75.36 \text{ ft}
$$
✔ Answer: 75.36 ft
---
Problem 3: Diameter = 14 in
$$
C = 3.14 \times 14 = 43.96 \text{ in}
$$
✔ Answer: 43.96 in
---
Problem 4: Radius = 15 in
$$
C = 2 \times 3.14 \times 15 = 94.2 \text{ in}
$$
✔ Answer: 94.2 in
---
Problem 5: Radius = 8 in
$$
C = 2 \times 3.14 \times 8 = 50.24 \text{ in}
$$
✔ Answer: 50.24 in
---
Problem 6: Diameter = 8 yd
$$
C = 3.14 \times 8 = 25.12 \text{ yd}
$$
✔ Answer: 25.12 yd
---
Problem 7: Radius = 18 in
$$
C = 2 \times 3.14 \times 18 = 113.04 \text{ in}
$$
✔ Answer: 113.04 in
---
Problem 8: Diameter = 10 yd
$$
C = 3.14 \times 10 = 31.4 \text{ yd}
$$
✔ Answer: 31.4 yd
---
Problem 9: Diameter = 4 yd
$$
C = 3.14 \times 4 = 12.56 \text{ yd}
$$
✔ Answer: 12.56 yd
---
✔ Final Answers:
| Problem | Circumference |
|--------|----------------|
| 1 | 113.04 yd |
| 2 | 75.36 ft |
| 3 | 43.96 in |
| 4 | 94.2 in |
| 5 | 50.24 in |
| 6 | 25.12 yd |
| 7 | 113.04 in |
| 8 | 31.4 yd |
| 9 | 12.56 yd |
---
🔍 Explanation Summary:
- When
diameter is given: Use $ C = \pi \times d $
- When
radius is given: Use $ C = 2\pi \times r $
- Always remember units — keep them consistent and include them in your answer.
- Use $ \pi \approx 3.14 $ unless instructed otherwise.
Let me know if you'd like these answers rounded to the nearest tenth or if you want exact values using $ \pi $.
Parent Tip: Review the logic above to help your child master the concept of circles circumference worksheet.
