Deriving the sum of interior angles in multiple ways | Maths

Starter quiz

A ______ is a flat (2D), closed figure made up of straight line segments.
- 'polygon' ✓
What is the size of ∠BCD?
- 73° ✓
- 84°
- 95°
- 108°
A hendecagon has 11 sides. The minimum number of triangles that it could be split into is ______.
- '9' ✓
A hexadecagon has 16 sides. Which calculation would find the sum of its interior angles?
- $14 \times 180$ ✓
- $14 \times 360$
- $16 \times 180$
- $16 \times 360$
Angles around a point sum to ______°.
- '360' ✓
Evaluate the expression $20(x − 2)$ when $x=5$ .
- '60' ✓