equilateral triangle – a triangle in which each side has the same length

(pronounced ee-kwihl-at-uh-ruhl)

To remember the meaning of equilateral triangle, use the following mnemonic:

The sides of the triangle were all equal (equilateral)

Equilateral starts with the word equal to remind you that all the sides of the triangle are equal.

Because all of the sides are equal with an equilateral triangle, it also means all three interior angles are equal, each measuring 60 degrees (the angle of any triangle must add up to exactly 180 degrees).

This makes the equilateral triangle one of the most symmetrical shapes in geometry, as it has three lines of symmetry.