Question

найдите значение выражения​

Answer 1

Ответ:

$\cos( \frac{\pi}{6} + \beta ) - \cos( \frac{\pi}{6} - \beta ) = \\ = - 2 \sin( \frac{ \frac{\pi}{6} + \beta + \frac{\pi}{6} - \beta }{2} ) \sin( \frac{ \frac{\pi}{6} + \beta - \frac{\pi}{6} + \beta }{2} ) = \\ = - 2 \sin( \frac{\pi}{6} ) \sin( \beta ) = - \frac{1}{2} \sin( \beta )$