Equilateral Triangle

A triangle which has all three of its sides equal in length.
Try this Drag the orange dots on each vertex to reshape the triangle. Notice it always remains an equilateral triangle. The sides AB, BC and AC always remain equal in length

An equilateral triangle is one in which all three sides are congruent (same length). Because it also has the property that all three interior angles are equal, it really the same thing as an equiangular triangle. See Equiangular triangles.

An equilateral triangle is simply a specific case of a regular polygon, in this case with 3 sides. All the facts and properties described for regular polygons apply to an equilateral triangle. See Regular Polygons


Constructing an Equilateral Triangle

It is possible to construct an equilateral triangle of a given side length using just a compass and straightedge. See Constructing an Equilateral Triangle

Other triangle topics


Perimeter / Area

Triangle types

Triangle centers

Congruence and Similarity

Solving triangles

Triangle quizzes and exercises