A circle has the circumference of 40 cm. What is the radius of the circle ?

The formula that gives the circumference of a circle
is:

Circumference = `pi` *2r, where r represents the radius
of th circle.

We'll replace the known values within the
formula of circumference:

40 = `pi`
*2r

r = 40/2`pi`

r =
20/`pi`

We'll take `pi` =
3.14

r = 20/3.14

r = 6.36
cm

The requested radius of the circle is of
6.36 cm.