# Equilateral triangle

**equilateral triangle**has, by definition, three sides that are equal in length.

In classical geometry it can easily be proved that an equilateral triangle is also *equiangular,* that is each of its three angles is equal; since another theorem states that the three angles of a triangle total 180°, each angle is 60°.

In some geometries (like sphere surface geometry) an equilateral triangle can have angles being more than 60° each: for example the North pole, the point situated 0°N 0°E and the point situated 0°N 90°E form an equilateral triangle with angles of 90°. This can be seen pointing for example the North Pole, Sao Tome & Principe and Singapore on a globe.

Note that it is only *triangles* that have the characteristic that equilateral means equiangular. For polygons of more than three sides, this is not true. A quadrilateral can have four equal sides—be a rhombus—without necessarily being a square.