Deriving the sum of interior angles in multiple ways

Maths

This unit gives pupils the opportunity to explore polygons and begin to generalise their understanding of interior/exterior angles in regular polygons. In the future unit, pupils will use the geometrical properties of a rhombus to perform various constructions

In this unit, pupils learnt how to calculate with angles at a point and angles on a straight line. In this unit, pupils extend their knowledge about angles in lines

Geometrical properties: polygons

Each time the number of sides of a polygon increases by 1, the sum of the interior angles increases by {{}}°.

The interior angles in 19-sided polygon sum to 3060°. Therefore the interior angles in a 20-sided polygon sum to {{}}°.

Which expression can be used to calculate the sum of interior angles in a polygon by substituting $$n$$ for the number of sides?

A triacontagon is a polygon with 30 sides. Which calculation finds the sum of its interior angles?

A tetracontagon is a polygon with 40 sides. Its interior angles sum to {{}}°.

A polygon has interior angles which sum to 720°. The polygon has {{ }} sides.

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

A hendecagon has 11 sides. The minimum number of triangles that it could be split into is {{ }}.

A hexadecagon has 16 sides. Which calculation would find the sum of its interior angles?

Evaluate the expression $$20(x − 2)$$ when $$x=5$$.

This lesson will soon be taken down.

Deriving the sum of interior angles in multiple ways

Lesson outcome