How do you compute radius?
For the triangle below, let x be the area of the circumcircle, and let y be the area of the incircle. Compute x - y.
Area of circumcircle==Pi * [a / sqrt(3)]^2
Area of incircle ==Pi * [a /(2*sqrt(3))]^2
x - y ==Pi * [a / sqrt(3)]^2 - Pi * [a /(2*sqrt(3))]^2
x - y==[Pi * a^2] / 4
