The Area of a Polygon with an Inscribed Circle

Marshall W. Buck, Robert L. Siddon

Heron's formula states that the area $K$ of a triangle with sides $a$, $b$, and $c$ is given by $$K=\sqrt{s(s-a)(s-b)(s-c)}$$ where $s$ is the semiperimeter $(a+b+c)/2$. Brahm…