Key learning points

1. The sum of the exterior angles of a polygon can be demonstrated using a point.
2. The sum of the exterior angles of a polygon can be proven using interior angles and the angles on a straight line.
3. The angle sum of a triangle can also be proven using exterior angles .
4. The size of the exterior angle of any polygon can be found using the sum of angles.

Keywords

• Interior angle - an angle formed inside a polygon by two of its edges.

• Exterior angle - an angle on the outside of a polygon between an extension of an edge and its adjacent edge.

• Supplementary angle - a pair of angles that sum to 180°.

Common misconception