Year 9 Circumference and Area of Circles Worksheet — Level 3 — Practice Set 4 — Answers
Answer sheet with worked solutions for the Year 9 area & perimeter worksheet.
Success TutoringWorksheetsAnswer sheetYear 9 · Mathematics · Area & PerimeterYear 9 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.Find the area of a semicircle with a radius of 8 cm, correct to 1 decimal place.
Answer: 100.5 cm2
- A = ½ × π × r2 = ½ × π × 64
- ≈ 100.5 cm2
2.A circle has a circumference of 40π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 20 cm; A = 400π cm2
- C = 2πr, so 2πr = 40π
- r = 20 cm
- A = πr2 = 400π cm2
3.A circle has a circumference of 20π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 10 cm; A = 100π cm2
- C = 2πr, so 2πr = 20π
- r = 10 cm
- A = πr2 = 100π cm2
4.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
5.A circle has a radius of 14 cm. Find its area, correct to 1 decimal place.
Answer: 615.8 cm2
- A = π × r2 = π × 142 = π × 196
- ≈ 615.8 cm2
6.A circle has a radius of 2 cm. Find its area, correct to 1 decimal place.
Answer: 12.6 cm2
- A = π × r2 = π × 22 = π × 4
- ≈ 12.6 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.Find the area of a semicircle with a radius of 19 cm, correct to 1 decimal place.
Answer: 567.1 cm2
- A = ½ × π × r2 = ½ × π × 361
- ≈ 567.1 cm2
9.Find the area of a semicircle with a radius of 7 cm, correct to 1 decimal place.
Answer: 77.0 cm2
- A = ½ × π × r2 = ½ × π × 49
- ≈ 77.0 cm2
10.Find the area of a semicircle with a radius of 6 cm, correct to 1 decimal place.
Answer: 56.5 cm2
- A = ½ × π × r2 = ½ × π × 36
- ≈ 56.5 cm2
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