(a)[4]
Write \(3\sqrt{2}\sin(x + 45^{\circ}) + \cos x\) in the form \(R\cos(x - \alpha)\), where \(R > 0\) and \(0^{\circ} < \alpha < 90^{\circ}\).
(b)[4]
Hence solve the equation \(3\sqrt{2}\sin(3\theta+45^\circ)+\cos 3\theta=-4\) for \(0^\circ\leq\theta\leq180^\circ\).