Question

помогите !!!!!!! !!!!!​

Answer 1

$1)(1+tg^{2}\alpha)(1-Cos^{2}\alpha)=\frac{1}{Cos^{2} \alpha }*Sin^{2}\alpha=tg^{2}\alpha\\\\2)tg(\alpha-\pi )*Ctg(\pi-\alpha)+Cos^{2}\alpha=-tg(\pi-\alpha)*(-Ctg\alpha)+Cos^{2}\alpha =tg\alpha*(-Ctg\alpha)+Cos^{2}\alpha=-1+Cos^{2}\alpha=-(1-Cos^{2}\alpha )=-Sin^{2} \alpha$