The angle between any two sides of an equilateral triangle is always $60$ degrees.

In an equilateral triangle, all three sides are of equal length, and all three internal angles are identical. The sum of the internal angles in any triangle is always $180$ degrees. Therefore, in an equilateral triangle, this total can be evenly distributed among the three angles. This means that each angle measures

To understand why this holds true, we can examine the defining properties of an equilateral triangle. By definition, an equilateral triangle has three sides that are all the same length. This inherent symmetry necessitates that each angle must also be equal; otherwise, the triangle would not maintain its balanced form. If one angle were different, the sides opposite those angles would not be equal, which would contradict the very definition of an equilateral triangle.

Additionally, we can confirm this using basic geometric principles. If you draw an equilateral triangle and then connect one vertex to the midpoint of the opposite side, you create two $30$-$60$-$90$ right triangles. In these right triangles, the angles measure $30$ degrees, $60$ degrees, and $90$ degrees. Since the original equilateral triangle consists of two such right triangles, it follows that the angle between any two sides of the equilateral triangle must indeed be $60$ degrees.

This consistent angle of $60$ degrees is a fundamental property of equilateral triangles and is essential for solving a variety of geometric problems and proofs that involve these shapes.