Question

Первое и второе пж, даю 80 балов​

Answer 1

Ответ:

Объяснение:

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

доказано