7th Grade Circumference and Area of Circles Worksheet — Level 3 — Practice Set 3 — Answers
Answer sheet with worked solutions for the 7th Grade area & perimeter worksheet.
Success TutoringWorksheetsAnswer sheet7th Grade · Mathematics · Area & Perimeter7th Grade Circumference and Area of Circles Worksheet — Level 3 — Practice Set 3 — Answers
Show your work. Use the π button on your calculator and round to 1 decimal place unless told otherwise.
1.A circle has a diameter of 34 cm. Find its area, correct to 1 decimal place.
Answer: 907.9 cm2
- r = 34 ÷ 2 = 17 cm
- A = π × r2 = π × 172 = π × 289
- ≈ 907.9 cm2
2.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
3.Find the area of a semicircle with a radius of 12 cm, correct to 1 decimal place.
Answer: 226.2 cm2
- A = ½ × π × r2 = ½ × π × 144
- ≈ 226.2 cm2
4.A circle has a radius of 5 cm. Find its area, correct to 1 decimal place.
Answer: 78.5 cm2
- A = π × r2 = π × 52 = π × 25
- ≈ 78.5 cm2
5.A circle has a circumference of 14π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 7 cm; A = 49π cm2
- C = 2πr, so 2πr = 14π
- r = 7 cm
- A = πr2 = 49π cm2
6.A circle has a circumference of 38π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 19 cm; A = 361π cm2
- C = 2πr, so 2πr = 38π
- r = 19 cm
- A = πr2 = 361π cm2
7.A circle has a circumference of 6π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 3 cm; A = 9π cm2
- C = 2πr, so 2πr = 6π
- r = 3 cm
- A = πr2 = 9π cm2
8.Find the area of a semicircle with a radius of 15 cm, correct to 1 decimal place.
Answer: 353.4 cm2
- A = ½ × π × r2 = ½ × π × 225
- ≈ 353.4 cm2
9.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
10.A circle has a circumference of 34π cm. Find its radius and its area (leave the area in terms of π).
Answer: r = 17 cm; A = 289π cm2
- C = 2πr, so 2πr = 34π
- r = 17 cm
- A = πr2 = 289π cm2
Marking tips
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