The formula for the circumference of a circle:
C = 2(π)(r)
To solve for r, just divide both sides by 2π.
C/2π = r
For this problem, you are given the C, so plug that into the equation.
8π = 2(π)(r)
Now to solve for r, just divide both sides by 2π
4 = r
The radius of the circle is 4.
