\[\boxed{\mathbf{1363}\mathbf{.}}\]
\[1)\sin{2x} = \frac{1}{2}\]
\[2x = ( - 1)^{n} \bullet \arcsin\frac{1}{2} + \pi n\]
\[2x = ( - 1)^{n} \bullet \frac{\pi}{6} + \pi n\]
\[x = \frac{1}{2} \bullet \left( ( - 1)^{n} \bullet \frac{\pi}{6} + \pi n \right)\]
\[x = ( - 1)^{n} \bullet \frac{\pi}{12} + \frac{\text{πn}}{2}.\]
\[Ответ:\ \ ( - 1)^{n} \bullet \frac{\pi}{12} + \frac{\text{πn}}{2}.\]
\[2)\cos{3x} = - \frac{\sqrt{2}}{2}\]
\[3x = \pm \left( \pi - \arccos\frac{\sqrt{2}}{2} \right) + 2\pi n\]
\[3x = \pm \left( \pi - \frac{\pi}{4} \right) + 2\pi n\]
\[3x = \pm \frac{3\pi}{4} + 2\pi n\]
\[x = \frac{1}{3} \bullet \left( \pm \frac{3\pi}{4} + 2\pi n \right)\]
\[x = \pm \frac{\pi}{4} + \frac{2\pi n}{3}.\]
\[Ответ:\ \ \pm \frac{\pi}{4} + \frac{2\pi n}{3}.\]
\[3)\ 2\ tg\ x + 5 = 0\]
\[2\ tg\ x = - 5\]
\[tg\ x = - 2,5\]
\[x = arctg( - 2,5) + \pi n.\]
\[Ответ:\ \ - arctg\ 2,5 + \pi n.\]