Решите пожалуйста!!!!!!!! Нужно срочно сверить ответ!!!!!!!!!!!!! sin( 7π/2- 2α)cos( (...

$sin(\frac{7\pi}{2}-2a)cos(\frac{6\pi}{2}-a)sina = sin(2\pi+\frac{3\pi}{2}-2a)cos(2\pi+\pi-a)sina = sin(\frac{3\pi}{2}-2a)cos(\pi-a)sina = -cos2a*(-cosa)sina = sina*cosa*cos2a = \frac{1}{2}sin2a*cos2a = \frac{1}{4}sin4a$

a = 3Pi/16

$\frac{1}{4}sin4a = \frac{1}{4}sin\frac{3\pi*4}{16} = \frac{1}{4}sin\frac{3\pi}{4} = \frac{1}{4}sin(\pi-\frac{\pi}{4}) = \frac{1}{4}sin\frac{\pi}{4} = \frac{1}{4}*\frac{\sqrt{2}}{2}=\frac{\sqrt{2}}{8}$