\[= \frac{\cos 0 - \cos{2nx}}{2\sin x} =\]
\[= \frac{1 - \cos{2nx}}{2} \bullet \frac{1}{\sin x} = \frac{\sin^{2}\text{nx}}{\sin x}.\]
\[Ответ:\ \ \frac{\sin^{2}\text{nx}}{\sin x}.\]
\[= \frac{\sin 0 + \sin{2nx}}{2\sin x} = \frac{\sin{2nx}}{2\sin x}.\]
\[Ответ:\ \ \frac{\sin{2nx}}{2\sin x}.\]