Question

РЕБЯТА , СРОЧНО ! ДАЮ 50 БАЛЛОВ!

Answer 1

$\frac{sin(\alpha-\beta)+sin\beta*cos\alpha}{tg\alpha} = \frac{sin(\alpha)*cos(\beta) - sin(\beta)*cos(\alpha)+sin\beta*cos\alpha}{tg\alpha} = \frac{sin\alpha*cos\beta}{ \frac{sin\alpha}{cos\alpha} } =\\= \frac{sin\alpha*cos\beta*cos\alpha}{sin\alpha} =cos\alpha*cos\beta$