Regular - GCSE Maths Definition

In GCSE Mathematics, a regular two-dimensional shape is a polygon that has every side, and therefore every (interior) angle, of equal size. For example, a regular pentagon would have five equal sides and five equal angles (the angles would all be 108°).

A regular triangle is called an equilateral triangle, and a regular quadrilateral is called a square. Beyond that, the word regular is put in front of the shape's general name; for example, regular octagon (8), regular decagon (10), etc.

Knowing, or identifying, shapes as being regular helps us solve problems where symmetry may be involved.