İpucu:
$$3\sin^22x+\sqrt{3}\sin 4x+\cos^22x=0$$
$$\Rightarrow$$
$$3\sin^22x+2\sqrt{3}\sin 2x\cdot\cos 2x+\cos^22x=0$$
$$\Rightarrow$$
$$(\sqrt{3}\sin 2x+\cos2x)^2=0$$
$$\Rightarrow$$
$$\sqrt{3}\sin 2x+\cos2x=0$$
$$\Rightarrow$$
$$\tan 2x=-\frac{1}{\sqrt{3}}$$