Question

Упростите выражение пожалуйста

Answer 1

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