Question

помогите срочноооооо

Answer 1

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