Question

срочно помоги минут 15 есть​

Answer 1

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