Question

помогите срочноооооо

Answer 1

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