Question

помогите пожааалуйста. никак не понимаю

Answer 1

$frac{sin2 alpha +2sin alpha cos2 alpha }{1+cos alpha +cos2 alpha +cos3 alpha }= frac{2sin alpha cos alpha +2sin alpha (cos^2 alpha -sin^2 alpha )}{1+cos alpha +cos^2 alpha -sin^2 alpha +cos2 alpha cos alpha -sin2 alpha sin alpha }= \ =frac{2sin alpha (cos alpha + cos^2 alpha -sin^2 alpha )}{cos alpha +2cos^2 alpha +cos alpha (cos^2 alpha-sin^2 alpha) -2sin^2 alpha cos alpha } =$

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