Question

 Упростить выражение

(cos2a/cosa)-(sin2a/sina)

 

 

 

Answer 1

$frac{cos2alpha }{cosalpha }-frac{sin2alpha }{sinalpha }=$

$=frac{cos2alpha*sinalpha-sin2alpha*cosalpha}{cosalpha*sinalpha}=$

$frac{sin(alpha-2alpha)}{cosalpha*sinalpha}=frac{sin(-alpha) }{cosalpha*sinalpha}=$

$=-frac{1}{cosalpha}$