Year 6 Circumference and Area of Circles Worksheet — Level 3 — Practice Set 4 — Answers
Answer sheet with worked solutions for the Year 6 area & perimeter worksheet.
Year 6 Circumference and Area of Circles Worksheet — Level 3 — Practice Set 4 — 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 circumference of 18π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 9 cm; A = 81π cm2
- C = 2πr, so 2πr = 18π
- r = 9 cm
- A = πr2 = 81π cm2
2.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
3.A circle has a diameter of 10 cm. Find its area, correct to 1 decimal place.
Answer: 78.5 cm2
- r = 10 ÷ 2 = 5 cm
- A = π × r2 = π × 52 = π × 25
- ≈ 78.5 cm2
4.A circle has a diameter of 24 cm. Find its area, correct to 1 decimal place.
Answer: 452.4 cm2
- r = 24 ÷ 2 = 12 cm
- A = π × r2 = π × 122 = π × 144
- ≈ 452.4 cm2
5.A circle has a radius of 18 cm. Find its area, correct to 1 decimal place.
Answer: 1017.9 cm2
- A = π × r2 = π × 182 = π × 324
- ≈ 1017.9 cm2
6.A circle has a diameter of 26 cm. Find its area, correct to 1 decimal place.
Answer: 530.9 cm2
- r = 26 ÷ 2 = 13 cm
- A = π × r2 = π × 132 = π × 169
- ≈ 530.9 cm2
7.A circle has a circumference of 24π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 12 cm; A = 144π cm2
- C = 2πr, so 2πr = 24π
- r = 12 cm
- A = πr2 = 144π cm2
8.A circle has a radius of 7 cm. Find its area, correct to 1 decimal place.
Answer: 153.9 cm2
- A = π × r2 = π × 72 = π × 49
- ≈ 153.9 cm2
9.A circle has a radius of 15 cm. Find its area, correct to 1 decimal place.
Answer: 706.9 cm2
- A = π × r2 = π × 152 = π × 225
- ≈ 706.9 cm2
10.A circle has a circumference of 16π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 8 cm; A = 64π cm2
- C = 2πr, so 2πr = 16π
- r = 8 cm
- A = πr2 = 64π 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.