Unit 4 Geometry Part 2 Lesson 4 Circumference And are of a Circle Quiz 1-8
1. If the diameter of a circle is 8 cm, what is the radius?
Answer: 4 cm
2. If the radius of a circle is 6 inches, what is the diameter?
Answer: 12 inches
3. Calculate the circumference of a circle with a diameter of 10 feet. Use 3.14 as an approximation for pi.
Answer: C = πd = 3.14 * 10 = 31.4 feet
4. Calculate the circumference of a circle with a radius of 5 meters. Use 3.14 as an approximation for pi.
Answer: C = 2πr = 2 * 3.14 * 5 = 31.4 meters
5. Calculate the area of a circle with a radius of 7 centimeters. Use 3.14 as an approximation for pi.
Answer: A = πr^2 = 3.14 * 7^2 = 3.14 * 49 = 153.86 square centimeters
6. Calculate the area of a circle with a diameter of 12 inches. Use 3.14 as an approximation for pi.
Answer: First find the radius: r = d/2 = 12/2 = 6 inches
Then calculate the area: A = πr^2 = 3.14 * 6^2 = 3.14 * 36 = 113.04 square inches
7. The circumference of a circle is 25 centimeters. Calculate the radius. Use 3.14 as an approximation for pi.
Answer: C = 2πr, so r = C / (2π) = 25 / (2 * 3.14) ≈ 25 / 6.28 ≈ 3.98 centimeters
8. The area of a circle is 78.5 square meters. Calculate the radius. Use 3.14 as an approximation for pi.
Answer: A = πr^2, so r^2 = A / π ≈ 78.5 / 3.14 ≈ 25
Then take the square root: r ≈ √25 ≈ 5 meters