Question

ДОКАЖИТЕ ТОЖДЕСТВО:
$frac{sin2a-sina}{1-cosa+cos2a}=tga$

Answer 1

$frac{sin2 alpha -sin alpha }{1-cos alpha +cos2 alpha }=frac{2sin alpha cos alpha -sin alpha }{cos^2 alpha +sin^2 alpha -cos alpha +cos^2 alpha -sin^2 alpha }=frac{sin alpha (2cos alpha -1)}{2cos^2 alpha -cos alpha }=\\=frac{sin alpha (2cos alpha -1)}{cos alpha (2cosalpha -1)}=frac{sin alpha }{cos alpha }=tg alpha .$