(i)[3]
Show that $(\sin \theta + \cos \theta)(1 - \sin \theta \cos \theta) \equiv \sin^3 \theta + \cos^3 \theta$.
(ii)[3]
Hence find the solutions of $(\sin \theta + \cos \theta)(1 - \sin \theta \cos \theta) = 3 \cos^3 \theta$ for $0^{\circ} \leq \theta \leq 360^{\circ}$.
(b(ii))[3]
Hence find the solutions of $(\sin \theta + \cos \theta)(1 - \sin \theta \cos \theta) = 3\cos^3 \theta$ for $0^{\circ} \leq \theta \leq 360^{\circ}$.