Question

.......................................................................1) sin^2 (п/2+a)- sin^2 ( п-а)
2) cos (a-B)+ cos ( п/2-а) * sin(-B)

Answer 1

1

$\sin {}^{2} ( \frac{\pi}{2} + \alpha ) - \sin {}^{2} (\pi - \alpha ) = \cos {}^{2} ( \alpha ) - \sin {}^{2} ( \alpha ) = \cos(2 \alpha )$

2

$\cos( \alpha - \beta ) + \cos( \frac{\pi}{2} - \alpha ) \times \sin( - \beta ) = \\ = \cos( \alpha ) \cos( \beta ) + \sin( \alpha ) \sin( \beta ) - \sin( \alpha ) \sin( \beta ) = \\ = \cos( \alpha ) \cos( \beta )$