Question

Помогите с матешей :^​

Answer 1

$dfrac{sin^2alpha}{1+cosalpha}+cos alpha =dfrac{(1-cos alpha)(1+cos alpha )}{1+cos alpha}+cos alpha=1-cos alpha +cos alpha =1$

$dfrac{2sin^2alpha cdot {rm ctg}, alpha}{cos^2alpha-sin^2alpha}=dfrac{2sin alphacos alpha}{cos2alpha}=dfrac{sin2alpha}{cos 2alpha}={rm tg}, 2alpha$