Question

Упростите
cosa*tga-sina*ctga

Answer 1

$\cos( \alpha ) \times tg( \alpha ) - \sin( \alpha ) \times ctg( \alpha ) = \\ = \cos( \alpha ) \times \frac{ \sin( \alpha ) }{ \cos( \alpha ) } - \sin( \alpha ) \times \frac{ \cos( \alpha ) }{ \sin( \alpha ) } = \\ = \sin( \alpha ) - \cos( \alpha )$