(i)[1]
Prove the identity $\frac{\sin \theta - \cos \theta}{\sin \theta + \cos \theta} = \frac{\tan \theta - 1}{\tan \theta + 1}$.
(ii)[4]
Hence solve the equation $\frac{\sin \theta - \cos \theta}{\sin \theta + \cos \theta} = -\frac{\tan \theta}{6}$, for $0^\circ \leq \theta \leq 180^\circ$.