How do you calculate radius when the have no radius and no diameter?

Answer:
You use the information that you do have, and a formula that relates it to the
radius or diameter of the circle. As an example: The circumference is very helpful
if you know it.
First answer by Alcohen2006. Last edit by Alcohen2006. Contributor trust: 1141 [recommend contributor recommended]. Question popularity: 2 [recommend question].