Heron's Formula

When given three sides of a triangle \(\; a,\ b, \ c\).

The area \(\;A\;\) of the triangle is given by:

Perimeter formula

\(p = a+b+c \)

Semiperimeter: \(\; s \equiv \frac{1}{2} p \)

Area formula

\(A= \sqrt { s(s-a)(s-b)(s-c) } \)

Semiperimeter: \(\; s \equiv \frac{1}{2} (a+b+c) \)