Tg²3x=3 помогите пожалуйста

Решите задачу:

$tg^23x=3\\\\ \frac{sin^23x}{cos^23x}=3\; \; ,\; \; \frac{1-cos6x}{1+cos6x}=3\; \; ,\; \; \frac{1-cos6x}{1+cos6x}-3=0\\\\ \frac{1-co6x-3-3cos6x}{1+cos6x}=0\; ,\; \; \frac{-4cos6x-2}{1+cos6x}=0\; \; ,\; \; \frac{2cos6x+1}{1+cos6x}=0\; ,\\\\ \left \{ {{2cos6x+1=0} \atop {1+cos6x\ne 0}} \right. \; ,\\\\cos6x\ne -1\; ,\; \; 6x\ne \pi +2\pi k\; ,\; \; x\ne \frac{\pi }{6}+\frac{\pi k}{3}\; ,\; k\in Z\\\\2cos6x=1\; ,\; \; cos6x=-\frac{1}{2} \; ,\\\\6x=\pm (\pi -\frac{\pi }{3})+2\pi n=\pm \frac{2\pi}{3}+2\pi n\; ,\; n\in Z$

$\underline {x=\pm \frac{\pi}{9}+\frac{\pi n}{3}\; ,\; n\in Z}$