Key learning points

1. Any polygon can be split into triangles.
2. Using these triangles you can demonstrate the rule for the interior angle sum of a polygon.
3. A missing interior angle in any polygon can be found.

Common misconception

Keywords

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

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

• Sum - The sum is the total when numbers are added together.