Intermediate November 2024 Unit 2 Q13
13. The interior angle of a regular polygon is 171°.
How many sides does the polygon have? [3]
| Scheme | Marks | Comments |
|---|---|---|
| (Number of sides =) \(\dfrac{360}{180 - 171}\) | M2 | Award M1 for sight of one of the following:
|
| = 40 (sides) | A1 | CAO. Allow an embedded answer but penalise -1 if contradicted by number of sides \(\neq\) 40. |
Alternative method
| Scheme | Marks | Comments |
|---|---|---|
| \(\dfrac{(n - 2) \times 180}{n} = 171\) or \(180n - 360 = 171n\) or equivalent | M1 | Brackets may be implied by later correct work. |
| \(9n = 360\) or equivalent | m1 | |
| \(n = 40\) (sides) | A1 | CAO. Allow an embedded answer but penalise -1 if contradicted by number of sides \(\neq\) 40. |