(a)[4]
By expanding $\tan(2\theta + 2\theta)$ first, show that the equation $\tan 4\theta = \frac{1}{2}\tan\theta$ can be rewritten as $\tan^4\theta + 2\tan^2\theta - 7 = 0$.
(b)[3]
Hence, solve the equation $\tan 4\theta = \frac{1}{2}\tan\theta$, for $0^\circ < \theta < 180^\circ$.