\[\boxed{\mathbf{679}\mathbf{.}}\]
\[1)\cos x \bullet \sin{5x} = - 1\]
\[Первая\ система:\]
\[\left\{ \begin{matrix} \cos x = - 1 \\ \sin{5x} = 1\ \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[\left\{ \begin{matrix} x = \pi - \arccos 1 + 2\pi n\ \\ 5x = \arcsin 1 + 2\pi n\ \ \ \ \ \ \ \ \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[\left\{ \begin{matrix} x = \pi + 2\pi n\ \ \\ 5x = \frac{\pi}{2} + 2\pi n \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} x = \pi + 2\pi n \\ x = \frac{\pi}{10} + \frac{2\pi n}{5} \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[корней\ нет.\]
\[Вторая\ система:\]
\[\left\{ \begin{matrix} \cos x = 1\ \ \ \ \ \\ \sin{5x} = - 1 \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[\left\{ \begin{matrix} x = \arccos 1 + 2\pi n\ \ \ \ \ \ \\ 5x = - \arcsin 1 + 2\pi n \\ \end{matrix} \right.\ \ \]
\[\left\{ \begin{matrix} x = 2\pi n\ \ \ \ \ \ \ \ \ \ \ \ \ \ \\ 5x = - \frac{\pi}{2} + 2\pi n \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} x = 2\pi n\ \ \ \ \ \ \ \ \ \ \ \ \ \ \\ x = - \frac{\pi}{10} + \frac{2\pi n}{5} \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[корней\ нет.\]
\[Ответ:\ \ решений\ нет.\]
\[2)\sin x \bullet \cos{3x} = - 1\]
\[Первая\ система:\]
\[\left\{ \begin{matrix} \sin x = 1\ \ \ \ \ \ \\ \cos{3x} = - 1 \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[\left\{ \begin{matrix} x = \arcsin 1 + 2\pi n\ \ \ \ \ \ \ \ \ \ \ \\ 3x = \pi - \arccos 1 + 2\pi n \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[\left\{ \begin{matrix} x = \frac{\pi}{2} + 2\pi n\ \ \\ 3x = \pi + 2\pi n \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} x = \frac{\pi}{2} + 2\pi n \\ x = \frac{\pi}{3} + \frac{2\pi n}{3} \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[корней\ нет.\]
\[Вторая\ система:\]
\[\left\{ \begin{matrix} \sin x = - 1 \\ \cos{3x} = 1 \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[\left\{ \begin{matrix} x = - \arcsin 1 + 2\pi n \\ 3x = \arccos 1 + 2\pi n\ \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[\left\{ \begin{matrix} x = - \frac{\pi}{2} + 2\pi n\ \ \\ 3x = 2\pi n\ \ \ \ \ \ \ \ \ \ \ \ \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} x = - \frac{\pi}{2} + 2\pi n \\ x = \frac{2\pi n}{3}\text{\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ } \\ \end{matrix} \right.\ \text{\ \ \ }\]
\[корней\ нет.\]
\[Ответ:\ \ решений\ нет.\]