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Shape: Equiangular


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

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

An equiangular (but not regular) hexagon: Image:EquiangularHexagon.png

Two equiangular octagons, one regular, one not: Image:EquiangularOctagon1.png Image:EquiangularOctagon2.png

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.


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

Related mathematical terms

Equilateral, Regular, Rectangle