(a)[3]
Demonstrate that the equation $3\tan^2 x - 3\sin^2 x - 4 = 0$ can be rewritten in the form $a\cos^4 x + b\cos^2 x + c = 0$, with $a$, $b$ and $c$ as the constants to determine.
(b)[4]
Hence solve the equation $3\tan^2 x - 3\sin^2 x - 4 = 0$ for $0^\circ \leq x \leq 180^\circ$.