Question

Упростить! 1) (cos^2a- sin^2a/cosa-sina) -tga * cosa​

Answer 1

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