Foundation November 2020 Paper 1R Q27
27 The diagram shows a regular octagon \(ABCDEFGH\).
Diagram NOT accurately drawn
Work out the size of angle \(HAC\).
(3)
| Scheme | Marks |
|---|---|
(Interior angle of octagon =) 180 – (360 ÷ 8) (= 135) or \(\dfrac{(8 - 2) \times 180}{8}\) (= 135) oe OR (exterior angle of octagon =) 360 ÷ 8 (=45) | M1 |
e.g. \(\dfrac{(8 - 2) \times 180}{8}\) (= 135) and (180 – “135”) ÷ 2 (=22.5) OR 360 ÷ 8 (= 45) and “45” ÷ 2 (= 22.5) | M1 |
| 112.5 | A1 |
| (3) | |
| (3 marks) |
Notes
M1: correct method to find interior or exterior angle of octagon (if labelled incorrectly do not award mark)
M1: correct method to find interior angle of octagon and base angle of triangle. (corrected from the printed mark scheme: “hexagon”)