What Is an Equilateral Triangle?
What Is an Equilateral Triangle?
An equilateral triangle is a triangle that has three equal angles and three sides the same length.
Note: The lines through the sides of the triangle in the image above indicate they are of equal length. The arcs indicate the angles are equal.
Dictionary Definition
The MerriamWebster dictionary defines an equilateral triangle as "a triangle in which all three sides are the same length."
Real Examples of Equilateral Triangles
Below are real examples of equilateral triangles.
In each case

All 3 sides are the same length.

All 3 angles are the same (60°).
Properties of Equilateral Triangles
The Interior Angles of an Equilateral Triangle
Each interior angle of an equilateral triangle is 60°.
The Symmetry of Equilateral Triangles
An equilateral triangle has 3 lines of symmetry.