Equilateral triangle

In geometry, an equilateral triangle is a triangle in which all three sides have the same length. In the familiar Euclidean geometry, an equilateral triangle is also equiangular; that is, all three internal angles are also congruent to each other and are each 60°. It is also a regular polygon, so it is also referred to as a regular triangle.

Equilateral triangle
Type	Regular polygon
Edges and vertices	3
Schläfli symbol	{3}
Coxeter–Dynkin diagrams
Symmetry group	D3
Area	${\displaystyle {\tfrac {\sqrt {3}}{4}}a^{2}}$
Internal angle (degrees)	60°