4MA0 Higher January 2015 Paper 3R Q14
14 The size of each interior angle of a regular polygon with \(n\) sides is 140°
Work out the size of each interior angle of a regular polygon with \(2n\) sides.
(5)
| Scheme | Marks |
|---|---|
| 180 – 140 or 40 | M1 |
| 360 ÷ “40” | M1 |
| \(n = 9\) | A1 |
| 180 – 360 ÷ (2ד9”) | M1 |
| 160 | A1 |
| (5 marks) |
Notes
M1: or \(180 \times (n - 2) \div n = 140\) oe
M1: or \(40n = 360\)
M1: or (180 × (2ד9” – 2)) ÷ 2ד9” or
(90 × (2 × 2 × “9” – 4)) ÷ 2ד9” (2880÷18)
Alternative scheme
| Scheme | Marks |
|---|---|
| 180 – 140 or 40 | M1 |
| “40” ÷ 2 | M1 |
| 20 | A1 |
| 180 – “20” | M1 |
| 160 | A1 |
Notes
M1: or \(180 \times (n - 2) \div n = 140\) oe