Question

ПОМОГИТЕ С НОМЕРОВ 349 , нужно сделать только : 2 . 4 ! СРОЧНО!

Answer 1

$2),, frac{sin 2 alpha -2cos alpha }{sin alpha -sin^2 alpha } = frac{2sin alpha cos alpha -2cos alpha }{sin alpha (1-sin alpha )} = frac{2cos alpha (sin alpha -1)}{sin alpha (1-sin alpha )} = frac{-2cos alpha }{sin alpha } =-2ctg alpha$

$frac{1-cos2 alpha +sin2 alpha }{1+cos2 alpha +sin2 alpha } cdot ctg alpha = frac{sin^2 alpha+cos^2alpha-cos^2alpha+sin^2alpha+2sinalphacos alpha }{sin^2alpha+cos^2alpha+cos^2alpha-sin^2alpha+2sinalphacosalpha} cdot ctg alpha = \ \ = frac{2sin^2alpha+2sinalphacos alpha}{2cos^2alpha+2sinalphacos alpha} cdot ctg alpha = frac{2sinalpha(sinalpha+cos alpha)}{2cosalpha(sinalpha+cosalpha)} cdot ctgalpha=tgalpha ctgalpha=1$