# The circumference of a circle 20cm. What is the radius of the circle?

$r = \frac{10}{\pi}$ $c m .$
Circumference of a circle is $C = 2 \pi r$, if $C = 20$ then
$20 = 2 \pi r$
$10 = \pi r$
$r = \frac{10}{\pi}$ $c m .$