Answer:
To find the radius with just the circumference is with this formula:
R = C ÷ (2 × π)
Or just divide the circumference by 2 times pi.
Here's an example:
The circumference is 26
R = C ÷ (2 × π)
R = 26 ÷ (2 × 3.14)
R = 26 ÷ 6.28
R = 4.140127388535032 or 4.1
Hope this helped