(a) By expanding \(\tan(2\theta + 2\theta)\), show that the equation \(\tan 4\theta = \frac{1}{2} \tan \theta\) can be expressed as \(\tan^4 \theta + 2 \tan^2 \theta - 7 = 0\).

(b) Solve the equation \(\tan 4\theta = \frac{1}{2} \tan \theta\) for \(0^\circ < \theta < 180^\circ\).