Question

Математика 10-11 класс

Answer 1

Ответ:

1.

$\sin( \frac{\pi}{2} - \alpha ) \times \cos( - \alpha ) + \sin( 2\pi + \alpha ) \times \sin(\pi - \alpha ) = \\ = \cos( \alpha ) \times \cos( \alpha ) + \sin( \alpha ) \times \sin( \alpha ) = \\ = { \cos}^{2} (\alpha ) +{ \sin}^{2} ( \alpha ) = 1$

2.

$ctg(180° - \alpha ) \times tg(2\pi + \alpha ) = - ctg( \alpha ) \times tg( \alpha ) = \\ = - \frac{1}{tg( \alpha )} \times tg (\alpha ) = - 1$