Circumference of a Circle

Front

What is the formula for the circumference of a circle?

Back

The circumference (C) of a circle is given by the formula: C = 2πr, where r is the radius.

Front

If the circumference of a circle is 36π units, what is the radius?

Back

The radius is 18 units.

Front

What is the circumference of a circle with a radius of 21 cm?

Back

The circumference is 131.9 cm.

Front

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

Back

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

Front

What is the circumference of a 12-inch pizza?

Back

The circumference is 37.68 inches.

Front

Find the circumference of a circle with a radius of 13.5 mm.

Back

The circumference is 84.78 mm.

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

How do you calculate 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 diameter of a circle with a radius of 10 cm?

Back

The diameter is 20 cm.

Front

If the radius of a circle is halved, what happens to the circumference?

Back

The circumference is also halved.