Geometry

Triangle Area (Heron)

Area from three side lengths.

Formula

Formula
A = s(s−a)(s−b)(s−c), s = a+b+c2

Variables

SymbolDefinitionType & rangeUnitsRole
a, b, c side lengths real number (ℝ) input
s semi-perimeter computed result result

Try it yourself

Interactive calculator
Result

Worked examples

Example 1
Givena = 3, b = 4, c = 5
Result6
Example 2
Givena = 7, b = 8, c = 9
Result26.83281573