$$3\ \sin^{2}x-4\sqrt{3}\sin\ x\ \cos\ x+3\ \cos^{2}x=0$$
$x=\pi n_{1}+\frac{\pi }{6}\text{, }n_{1}\in \mathrm{Z}$
$x=\pi n_{1}+\frac{\pi }{3}\text{, }n_{1}\in \mathrm{Z}$
