Year 8 Circumference and Area of Circles Worksheet — Level 3 — Practice Set 2 — Answers
Answer sheet with worked solutions for the Year 8 area & perimeter worksheet.
Year 8 Circumference and Area of Circles Worksheet — Level 3 — Practice Set 2 — Answers
Show your working. Use the π button on your calculator and round to 1 decimal place unless told otherwise.
1.A circle has a radius of 13 cm. Find its area, correct to 1 decimal place.
Answer: 530.9 cm2
- A = π × r2 = π × 132 = π × 169
- ≈ 530.9 cm2
2.A circle has a diameter of 22 cm. Find its area, correct to 1 decimal place.
Answer: 380.1 cm2
- r = 22 ÷ 2 = 11 cm
- A = π × r2 = π × 112 = π × 121
- ≈ 380.1 cm2
3.A circle has a circumference of 4π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 2 cm; A = 4π cm2
- C = 2πr, so 2πr = 4π
- r = 2 cm
- A = πr2 = 4π cm2
4.A circle has a diameter of 40 cm. Find its area, correct to 1 decimal place.
Answer: 1256.6 cm2
- r = 40 ÷ 2 = 20 cm
- A = π × r2 = π × 202 = π × 400
- ≈ 1256.6 cm2
5.A circle has a circumference of 32π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 16 cm; A = 256π cm2
- C = 2πr, so 2πr = 32π
- r = 16 cm
- A = πr2 = 256π cm2
6.A circle has a circumference of 12π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 6 cm; A = 36π cm2
- C = 2πr, so 2πr = 12π
- r = 6 cm
- A = πr2 = 36π cm2
7.Find the area of a semicircle with a radius of 2 cm, correct to 1 decimal place.
Answer: 6.3 cm2
- A = ½ × π × r2 = ½ × π × 4
- ≈ 6.3 cm2
8.A circle has a radius of 12 cm. Find its area, correct to 1 decimal place.
Answer: 452.4 cm2
- A = π × r2 = π × 122 = π × 144
- ≈ 452.4 cm2
9.A circle has a circumference of 22π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 11 cm; A = 121π cm2
- C = 2πr, so 2πr = 22π
- r = 11 cm
- A = πr2 = 121π cm2
10.Find the area of a semicircle with a radius of 13 cm, correct to 1 decimal place.
Answer: 265.5 cm2
- A = ½ × π × r2 = ½ × π × 169
- ≈ 265.5 cm2
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.