Area of inscribed circle

[@andrepiotrowski5668]

The radiusses of the inner circle and the outer circles of a pythagorean triangle are always positive integers. Because of r_a+r_b = c and r_a < r_b the possibilities are r_a = 1, r_b =4 or r_a = 2, r_b = 3. Because of r_i < r_a outer circles have to be greater than 1, so the first case is not possible. It follows immediately (r_a = 2, r_b = 3 and) r_i = 1. Thus the area of the inner circle is π.