Question

Помогите, пожалуйста

Answer 1

$sin^2 alpha *tg alpha +cos^2 alpha *ctg alpha +sin2 alpha = \ \ =sin^2 alpha * frac{sin alpha }{cos alpha }+cos^2 alpha * frac{cos alpha }{sin alpha }+2sin alpha cos alpha = \ \ = frac{sin^3 alpha }{cos alpha }+ frac{cos^3 alpha }{sin alpha }+2sin alpha cos alpha = \ \ = frac{sin^4 alpha +cos^4 alpha +2sin^2 alpha cos^2 alpha }{sin alpha cos alpha }= frac{(sin^2 alpha +cos^2 alpha )^2}{ frac{1}{2}*2sin alpha cos alpha }=$
$= frac{1^2}{ frac{1}{2}*sin2 alpha }= frac{2}{sin2 alpha }$
Ответ: 2)