A polygon is a flat (2D), closed figure made up of straight line segments.

A regular polygon has sides that are all equal and interior (inside) angles that are all equal.

An interior angle is an angle formed inside a polygon by two of its edges.

An exterior angle is an angle on the outside of a polygon between an extension of an edge and the adjacent edge.

Checking and securing understanding of exterior angles

Maths

In this unit, pupils applied their understanding of angles to solve increasingly complex problems. In the future unit, pupils will use their mathematical reasoning to derive and use various circle theorems. 

In the prior unit, pupils learnt how to identify corresponding, alternate and co-interior angles. In this unit, pupils use their knowledge of these angles to reason through and solve more complicated problems.

Angles

An {{ }} angle is an angle on the outside of a polygon between an extension of an edge and the adjacent edge.

The exterior angles of any polygon sum to {{}}°.

An interior angle and its adjacent exterior angle sum to {{}}°.

The size of each exterior angle of a regular pentagon is {{}}°.

A regular polygon has exterior angles of 40°. The polygon has {{ }} sides.

Which of these exterior angles are possible for a regular polygon?

An {{}} angle is an angle formed inside a polygon by two of its edges.

Three of the interior angles of a quadrilateral are 80°, 90° and 45°.  The size of the fourth interior angle is {{}}°.

The interior angles of a dodecagon (12 sides) sum to {{}}°.

Each interior angle of a regular octagon is {{}}°.

A regular polygon has interior angles of size 162°. The polygon has {{}} sides.

Which interior angles are possible in a regular polygon?

Starter Quiz