- In this question you must show all stages of your working.
Solutions relying entirely on calculator technology are not acceptable.
- Show that
$$\cos 3 A \equiv 4 \cos ^ { 3 } A - 3 \cos A$$
- Hence solve, for \(- 90 ^ { \circ } \leqslant x \leqslant 180 ^ { \circ }\), the equation
$$1 - \cos 3 x = \sin ^ { 2 } x$$