t_2=\frac{\sqrt{3} }{2} \\x=\pm \frac{\pi }{6} +2\pi k" alt="\cos x=t\\2t^2-3\sqrt{3} t+3=0\\D=3\\t_1=\sqrt{3} , \\\cos x=\sqrt{3}, \\x\in \varnothing \\
t_2=\frac{\sqrt{3} }{2} \\x=\pm \frac{\pi }{6} +2\pi k" align="absmiddle" class="latex-formula">