Question

Помогите решить уравнение , срочно!!! необходимо упростить

Answer 1

$frac{cosalpha-2sinalpha}{sinalpha+cosalpha}-frac{2-cos^2alpha}{cos2alpha}=\ frac{cosalpha-2sinalpha}{sinalpha+cosalpha}-frac{2sin^2alpha+2cos^2alpha-cos^2alpha}{cos^2alpha-sin^2alpha}=\ =frac{cosalpha-2sinalpha}{sinalpha+cosalpha}-frac{2sin^2alpha+cos^2alpha}{(cosalpha-sinalpha)(sinalpha+cosalpha)}=\ frac{cos^2-sinalphacosalpha-2sinalphacosalpha+2sin^2alpha-2+cos^2alpha}{cos^2alpha-sin^2alpha}=$
$frac{2cos^2alpha+2sin^2alpha-2-3sinalphacosalpha}{cos2alpha}=frac{-frac32sin2alpha}{cos2alpha}=-frac32tg2alpha$