# Heron's Formula For The Area of Any Triangle *Heron's Formula* is **used to calculate the area of any triangle given the length of its three sides**. Let $s$ be the semi-perimeter of the triangle ($s=\frac{a+b+c}{2}$), then the triangle's area $A$ is $A=\sqrt{s(s-a)(s-b)(s-c)}$ ^45thfd It can be thought of a special case of the [[Brahmagupta's Formula For The Area of Any Cyclic Quadrilateral|Brahmagupta's Formula]], where a triangle is a cyclic quadrilateral whose fourth side has length of 0.