Question

скоротіть вираз:

$\frac{1-cos^{2}\alpha }{1-sin^{2} \alpha } +tg\alpha *ctg\alpha$

Answer 1

$\displaystyle\bf\\\frac{1-Cos^{2} \alpha }{1-Sin^{2} \alpha } +tg\alpha \cdot \ Ctg\alpha =\frac{Sin^{2}\alpha }{Cos^{2} \alpha } +1=tg^{2} \alpha +1=\frac{1}{Cos^{2} \alpha }$