Equilateral Triangle - GCSE Maths Definition

What is an equilateral triangle?

In GCSE Maths, an equilateral triangle is a special type of triangle in which all three sides have the same (equal) length. Each of the three internal angles in an equilateral triangle is equal to 60°.

Other properties of an equilateral triangle include having three lines of symmetry (from each corner to the middle of the opposite side) and having rotational symmetry of order 3 (rotating it by 120° gives the same triangle). An equilateral triangle is a special type of isosceles triangle, but cannot be a scalene triangle, nor a right-angled triangle.