In this worksheet, decide whether a polygon is **regular **or **irregular**.

The word **polygon **comes from the Greek language:

*polús *means *many *and *gõnía *means *angles*.

A polygon is a flat shape with straight sides that are joined to form a closed shape. It will have several angles.

**Regular polygons**

A regular polygon is one in which all the sides are equal in length and all the interior angles are equal in size.

A **square **has 4 equal sides and 4 equal angles of 90°.

A **regular pentagon** has 5 equal sides and 5 equal angles of 108°.

A **regular octagon** has 8 equal sides and 8 equal angles of 135°.

**Irregular polygons**

An irregular polygon is one in which either all the sides are **not** equal in length and/or all the interior angles are not equal in size.

This triangle is **scalene**. It has sides of 3 different lengths and 3 different angles. It is **irregular**.

This pentagon has three 90° angles, but also two angles which are larger. The sides are of differing lengths. It is **irregular**.