Question

На фото задание
Буду благодарен

Answer 1

$frac{1-sin^{2} alpha }{1-cos^{2} alpha } +tg alpha ctg alpha = frac{sin^{2} alpha+cos^{2} alpha -sin^{2} alpha}{sin^{2} alpha+cos^{2} alpha -cos^{2} alpha } +1= frac{cos^{2} alpha }{sin^{2} alpha} +1=tg^{2} alpha+1$
$frac{tg alpha}{tg alpha ctg alpha+tg^2 alpha} = frac{tg alpha}{1+tg^2 alpha} =frac{0.5*2 tg alpha}{1+tg^2 alpha} =0.5 tg2 alpha$