(a)[3]
Express $4 \cos x - \\sin x$ in the form $R \cos(x + \alpha)$, where $R > 0$ and $0^\circ < \alpha < 90^\circ$. Give the exact value of $R$ and state $\alpha$ correct to 2 decimal places.
(b)[5]
Hence solve the equation $4 \cos 2x - \sin 2x = 3$ over $0^\circ < x < 180^\circ$.