8th Grade Circumference and Area of Circles Worksheet — Level 3 — Practice Set 4 — Answers
Answer sheet with worked solutions for the 8th Grade area & perimeter worksheet.
Success TutoringWorksheetsAnswer sheet8th Grade · Mathematics · Area & Perimeter8th Grade Circumference and Area of Circles Worksheet — Level 3 — Practice Set 4 — Answers
Show your work. 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 15 cm, correct to 1 decimal place.
Answer: 353.4 cm2
- A = ½ × π × r2 = ½ × π × 225
- ≈ 353.4 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 4 cm. Find its area, correct to 1 decimal place.
Answer: 12.6 cm2
- r = 4 ÷ 2 = 2 cm
- A = π × r2 = π × 22 = π × 4
- ≈ 12.6 cm2
4.Find the area of a semicircle with a radius of 9 cm, correct to 1 decimal place.
Answer: 127.2 cm2
- A = ½ × π × r2 = ½ × π × 81
- ≈ 127.2 cm2
5.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
6.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
7.A circle has a diameter of 6 cm. Find its area, correct to 1 decimal place.
Answer: 28.3 cm2
- r = 6 ÷ 2 = 3 cm
- A = π × r2 = π × 32 = π × 9
- ≈ 28.3 cm2
8.A circle has a radius of 16 cm. Find its area, correct to 1 decimal place.
Answer: 804.2 cm2
- A = π × r2 = π × 162 = π × 256
- ≈ 804.2 cm2
9.Find the area of a semicircle with a radius of 20 cm, correct to 1 decimal place.
Answer: 628.3 cm2
- A = ½ × π × r2 = ½ × π × 400
- ≈ 628.3 cm2
10.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
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