Circumference of a Circle

Front

What is the formula for the circumference of a circle?

Back

C = 2πr or C = πd, where C is circumference, r is radius, and d is diameter.

Front

If the radius of a circle is 15 yards, what is the circumference?

Back

94.2 yards (C = 2πr = 2 * 3.14 * 15).

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the radius (d = 2r).

Front

If a circle has a diameter of 40 feet, what is its radius?

Back

20 feet (r = d/2).

Front

What is the circumference of a circle with a diameter of 17 inches?

Back

53.38 inches (C = πd = 3.14 * 17).

Front

How do you convert diameter to radius?

Back

Divide the diameter by 2 (r = d/2).

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

If the radius of a circle is 10 feet, what is the diameter?

Back

20 feet (d = 2r).

Front

What is the circumference of a circle with a radius of 5 cm?

Back

31.4 cm (C = 2πr = 2 * 3.14 * 5).

Front

How do you find the circumference if you only have the radius?

Back

Use the formula C = 2πr.