Higher November 2020 Paper 1 Q22
22.
Diagram not drawn to scale
Calculate the length of AC.
Give your answer as a surd in its simplest form. [5]
| Scheme | Marks | Comments |
|---|---|---|
| \(\cos 60^\circ = \dfrac{1}{2}\) si | B1 | |
| \((AC^2 =)\ 4^2 + 12^2 - 2(4)(12)\cos 60\) | M1 | Allow even if AC = |
| \((AC^2 =)\ 112\) | M1 | FT ‘their cos 60’ provided \(-1 \lt\) ‘their cos 60’ \(\lt 1\) |
| \(AC = \sqrt{112}\) | A1 | FT ‘their cos 60’ provided ‘their 112’ > 0 |
| \(AC = 4\sqrt{7}\) | A1 | CAO |
| (5) |