Question

What is the radius of this circle if the circumference is 18π cm?

C=18π cm

3 cm
9 cm
18 cm
36 cm

Answer 1

9 cm

Explanation:

Circumference of a circle is given by

C = pi * 2 *r

18 pi = pi * 2 *r

Divide each side by pi

18 = 2 r

Divide each side by 2

18/2 = 2r/2

9 = r

The radius is 9 cm