(i)[3]
Write $2\sin\theta - \cos\theta$ in the form $R\sin(\theta - \alpha)$, where $R > 0$ and $0^\circ < \alpha < 90^\circ$, and give the exact value of $R$ together with $\alpha$ correct to $2$ decimal places.
(ii)[4]
Hence solve the equation $2\sin\theta - \cos\theta = -0.4$, and give every solution in the interval $0^\circ \leq \theta \leq 360^\circ$.