One of the formulas to find the area of a triangle is a = r*s. Where the r is the radius of the circle inscribed the triangle, and s being the semi perimeter. (s = p/2) Prove that the same formula works for a square.

Answer 1

perimeter=4r
semiperimeter s=2r

area=r*s=r*(p/2)=r*2r/2=r^2