Higher November 2017 Paper 1 Q20
20 The table shows some values of \(x\) and \(y\) that satisfy the equation \(y = a\cos x^\circ + b\)
| \(x\) | 0 | 30 | 60 | 90 | 120 | 150 | 180 |
|---|---|---|---|---|---|---|---|
| \(y\) | 3 | \(1 + \sqrt{3}\) | 2 | 1 | 0 | \(1 - \sqrt{3}\) | \(-1\) |
Find the value of \(y\) when \(x = 45\) (4)
| Answer | Mark | Notes |
|---|---|---|
| \(1+\sqrt{2}\) | B1 | for a value for a known trigonometric ratio stated |
| P1 | for process to form 2 equations in \(a\) and \(b\) or one correct value stated | |
| P1 | for complete process to solve to reach \(a = 2\) and \(b = 1\) | |
| A1 | for \(1+\sqrt{2}\) oe |