Question

cos(п/14)cos(19п/28)-sin(п/14)sin (19п/28)

Answer 1

Ответ:

$\cos( \frac{\pi}{14?} ) \cos( \frac{19\pi}{28?} ) - \sin( \frac{\pi}{14?} ) \sin( \frac{19\pi}{28?} ) = \cos(( \frac{3\pi}{4} )) = - \frac{ \sqrt{2} }{2}$