(i) Show that the equation \((\sin \theta + 2 \cos \theta)(1 + \sin \theta - \cos \theta) = \sin \theta(1 + \cos \theta)\) may be expressed as \(3 \cos^2 \theta - 2 \cos \theta - 1 = 0\).

(ii) Hence solve the equation \((\sin \theta + 2 \cos \theta)(1 + \sin \theta - \cos \theta) = \sin \theta(1 + \cos \theta)\) for \(-180^\circ \leq \theta \leq 180^\circ\).