Radius of incircle and circumradius of a triangle

Radius of incircle and circumcircle of an equilateral triangle

Ratio of inradius to circumradius in triangle

In triangle ABC, let angle C = pi//2 . If r is the inradius and R is circumradius of the triangle, then 2(r + R) is equal to

Find the radius of incircle it the sides of triangle are (i) (13,14,15)