Question

1)cos^2a-1/sin^2a+tga×ctga
2)tga×cosa/1+ctg^2a у решить

Answer 1

$1)\frac{Cos^{2}\alpha-1}{Sin^{2}\alpha}+tg\alpha*Ctg\alpha=\frac{-Sin^{2}\alpha}{Sin^{2}\alpha}+1=-1+1=0$

$2)\frac{tg\alpha*Cos\alpha}{1+Ctg^{2}\alpha }=\frac{\frac{Sin\alpha}{Cos\alpha}*Cos\alpha}{\frac{1}{Sin^{2}\alpha}}=Sin\alpha*Sin^{2}\alpha=Sin^{3}\alpha$