Circumference and Area of a Circle

Front

What is the formula for the circumference of a circle?

Back

The circumference (C) of a circle is calculated using the formula C = 2πr, where r is the radius of the circle.

Front

What is the formula for the area of a circle?

Back

The area (A) of a circle is calculated using the formula A = πr², where r is the radius of the circle.

Front

If the radius of a circle is 10 inches, what is its circumference?

Back

Using the formula C = 2πr, the circumference is C = 2π(10) = 62.83 inches.

Front

If the radius of a circle is 5 feet, what is its area?

Back

Using the formula A = πr², the area is A = π(5)² = 78.54 square feet.

Front

What is the relationship between diameter and radius in a circle?

Back

The diameter (d) of a circle is twice the radius (r), so d = 2r.

Front

How do you convert the circumference from inches to yards?

Back

To convert inches to yards, divide the number of inches by 36, since there are 36 inches in a yard.

Front

What is the circumference of a circle with a diameter of 12 meters?

Back

Using the formula C = πd, the circumference is C = π(12) = 37.70 meters.

Front

How do you find the radius if you know the circumference?

Back

To find the radius from the circumference, use the formula r = C/(2π).

Front

What is the area of a circle with a radius of 3 mm?

Back

Using the formula A = πr², the area is A = π(3)² = 28.27 mm².

Front

What is the circumference of a circle with a radius of 4 yards?

Back

Using the formula C = 2πr, the circumference is C = 2π(4) = 25.13 yards.