Circumference is the distance around the edge of a circle, radius is the distance from the center of a circle to the edge of the circle.
To find circumference you use the formula
C = 2(r)(pi)
Where
C = circumference
r = radius
pi =
The 2 is there because of you multiply the radius by 2 you will get the diameter, the distance across the entire circle that goes through the center of the circle.
In this problem you have the value of C, therefore
5 = 2r
Now you can solve.
5 = 2r
5 = 2r
5/2 = r = radius
