\[\lbrack 0;\ 3\pi\rbrack.\]
\[1)\ 2\cos x + \sqrt{3} = 0\]
\[2\cos x = - \sqrt{3}\]
\[\cos x = - \frac{\sqrt{3}}{2}\]
\[x = \pm \frac{5\pi}{6} + 2\pi n.\]
\[Ответ:\ \ \frac{5\pi}{6};\ \frac{7\pi}{6};\ \frac{17\pi}{6}.\]
\[2)\ \sqrt{3} - \sin x = \sin x\]
\[2\sin x = \sqrt{3}\]
\[\sin x = \frac{\sqrt{3}}{2}\]
\[x = ( - 1)^{n} \bullet \frac{\pi}{3} + \pi\text{n.}\]
\[Ответ:\ \ \frac{\pi}{3};\ \frac{2\pi}{3};\ \frac{7\pi}{3};\ \frac{8\pi}{3}.\]
\[3)\ 3\ tg\ x = \sqrt{3}\]
\[tg\ x = \frac{\sqrt{3}}{3}\]
\[x = \frac{\pi}{6} + \pi\text{n.}\]
\[Ответ:\ \ \frac{\pi}{6};\ \frac{7\pi}{6};\ \frac{13\pi}{6}.\]
\[4)\cos x + 1 = 0\]
\[\cos x = - 1\]
\[x = \pi + 2\pi\text{n.}\]
\[Ответ:\ \ \pi;\ 3\pi.\]