# Shape: Equiangular

## Meaning

The term *equiangular* indicates that, in some figure, the angles are equal. It can be used to describe polygons, such as an equiangular pentagon.

The fact that the *angles* of a figure are congruent does not automatically mean that the *sides* are.

An equiangular (but not regular) hexagon:

Two equiangular octagons, one regular, one not:

If a quadrilateral is equiangular, it is a rectangle.

## Mathematical background

In the case of triangles, being equiangular *requires* that the triangle also be equilateral. That is, every equiangular triangle is a regular triangle. However, this is not the case for all polygons. For example, a rectangle is equiangular -- all four angles are 90° -- but need not be square (need not have all four sides the same length). Thus, not all equiangular quadrilaterals are equilateral and so are not all regular.

## Etymology

The prefix **equi-** is from Latin and means 'equal'.

## Related mathematical terms

Equilateral, Regular, Rectangle