The Compendium Geometry is an eBook providing facts, formulas and explanations about geometry.

Equilateral Triangle

An equilateral triangle is a triangle with all sides being equal:

a = b = c

As a consequence all angles are 60, and all heights, all medians, and all angle bisectors are also of equal length and are located on top of each other. There are three axes of symmetry, which partition the triangle into two congruent right triangles.

The following table shows the most important properties of an equilateral triangle:

Property Formula
Height h
Radius of the incircle r
Radius of the circumcircle r
Area A


Last Update: 2010-12-06