Quiz About Area And Circumference Of A Circle

1) A circle has a radius of 12 inches. What is the area of the circle?

400.14 inches squared

452.16 inches squared

75.36 inches squared

12 x 12 x 3.14

Explanation

12 x 12 x 3.14

2) The radius is always half of the diameter.

True

False

The statement is true because the radius of a circle is defined as the distance from the center of the circle to any point on its circumference. The diameter, on the other hand, is the distance across the circle passing through the center. Since the diameter is twice the length of the radius, it follows that the radius is always half of the diameter.

Explanation

The statement is true because the radius of a circle is defined as the distance from the center of the circle to any point on its circumference. The diameter, on the other hand, is the distance across the circle passing through the center. Since the diameter is twice the length of the radius, it follows that the radius is always half of the diameter.

3) Molly is making pizza for supper and wants to cover the top of the pizza with sauce. She has measured the radius of the pizza to be 5 inches, how many square inches will the sauce cover?

31.4 inches squared

78.5 inches squared

15.7 inches squared

The correct answer is 78.5 inches squared. To find the area of the top of the pizza, we need to use the formula for the area of a circle, which is A = πr^2. Given that the radius of the pizza is 5 inches, we can substitute this value into the formula to get A = π(5^2) = π(25) = 78.5 inches squared.

Explanation

The correct answer is 78.5 inches squared. To find the area of the top of the pizza, we need to use the formula for the area of a circle, which is A = πr^2. Given that the radius of the pizza is 5 inches, we can substitute this value into the formula to get A = π(5^2) = π(25) = 78.5 inches squared.

4) The radius of a circle is 3 inches. What is the area?

9.25 inches squared

20.28 inches squared

28.26 inches squared

3 x 3 x 3.14

Explanation

3 x 3 x 3.14

5) The diameter of a circle is 8 centimeters. What is the area?

50.24 centimeters squared

64 centimeters squared

16.24 centimeters squared

Make sure you change the diameter to a radius. (divide by 2)

Explanation

Make sure you change the diameter to a radius. (divide by 2)

6) Mark has a circular swimming pool with are radius of 7 feet. If he wants a cover to go over the pool what is the least amount of material needed to cover the pool?

43.96 feet squared

21.98 feet squared

153.86 feet squared

7 x 7 x 3.14

Explanation

7 x 7 x 3.14

7) Sam has baked a circular cake. The cake has a diameter of 10 inches. Sam needs to know how much icing it will take to cover the top of the cake, which of the following was does Sam need to use to figure this out?

10 x 3.14

5 x 2 x 3.14

5 x 5 x 3.14

Area = radius x radius x pi

Explanation

Area = radius x radius x pi

8) The chord is the longest diameter in a circle.

True

False

The statement is false because a chord is not the longest diameter in a circle. A diameter is a chord that passes through the center of the circle, and it is always longer than any other chord in the circle. Therefore, the longest diameter in a circle is the one that passes through the center, not any other chord.

Explanation

The statement is false because a chord is not the longest diameter in a circle. A diameter is a chord that passes through the center of the circle, and it is always longer than any other chord in the circle. Therefore, the longest diameter in a circle is the one that passes through the center, not any other chord.

9) A cicular stool needs to be covered with new fabric. If the diameter of the stool is 2 feet, how much material is needed to cover the stool?

12.56 feet squared

6.28 feet squared

3.14 feet squared

The correct answer is 3.14 feet squared. To calculate the amount of fabric needed to cover the circular stool, we need to find the area of the circle. The formula for the area of a circle is A = πr^2, where A is the area and r is the radius. In this case, the diameter of the stool is given as 2 feet, so the radius is 1 foot. Plugging this value into the formula, we get A = 3.14 * 1^2 = 3.14 feet squared. Therefore, 3.14 feet squared of fabric is needed to cover the stool.

Explanation

The correct answer is 3.14 feet squared. To calculate the amount of fabric needed to cover the circular stool, we need to find the area of the circle. The formula for the area of a circle is A = πr^2, where A is the area and r is the radius. In this case, the diameter of the stool is given as 2 feet, so the radius is 1 foot. Plugging this value into the formula, we get A = 3.14 * 1^2 = 3.14 feet squared. Therefore, 3.14 feet squared of fabric is needed to cover the stool.

10) Pam's mom is fixing cookies for her class. She wants to put icing on the cookies. The radius of the cookies is 2 inches. She is making 20 cookies, what is the area that the icing will cover if she icings all 20 cookies?

251.2 inches squared

125.6 inches squared

12.56 inches squared

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Explanation

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