Foundation November 2020 Paper 1 Q21
21 Here is a 10-sided polygon.
Diagram NOT accurately drawn
Work out the value of \(x\).
(4)
| Scheme | Marks |
|---|---|
| (10 – 2) × 180 oe (= 1440) or (6 – 2) × 180 oe (= 720) | M1 |
| ‘1440’ – 148 – 2×150 – 2×168 – 2×134 – 2×125 (= 138) or ‘1440’ – 1302 (= 138) or ‘720’ – 148÷2 – 150 – 168 – 134 – 125 (= 69) or ‘720’ – 651 (= 69) | M1 |
| 360 – ‘138’ or 360 – 2 × ‘69’ | M1 |
| 222 | A1 |
| (4) | |
| (4 marks) |
Notes
M1: for a method to find the sum of the interior angles of a decagon or a hexagon
M1: Allow omission of one angle
Alternative method (exterior angles)
| Scheme | Marks |
|---|---|
| 360 – 2×(180 – 125) – 2×(180 – 134) – 2×(180 – 168) – 2×(180 – 150) – (180 – 148) or 360 – 2×55 – 2×46 – 2×12 – 2×30 – 32 | M2 |
| 180 + ‘42’ | M1 |
| 222 | A1 |
M2: If not M2 then award M1 for at least 3 of (180 – 125), (180 – 134), (180 – 168), (180 – 150), (180 – 148) or at least 3 of 55, 46, 12, 30, 32