The radius of a circle is a line drawn from the direct center of the circle to its outer edge. C 4pA. To calculate the radius of a circle by using the circumference take the circumference of the circle and divide it by 2 times p.
R radius d diameter.
For a circle with a circumference of 15. There are a three formulas to finding the radius depending on whether or not you know the diameter circumference or. Insert the value for the radius and perform the remaining calculations as follows. A radius can be drawn in any direction from the central point.