Question

докажите тождество!!!!!
2sin^2α+2cos^2α+tg^2α+ctg^2α= 1/sin^2α*cos^2α

Answer 1

$2Sin^{2}\alpha+2Cos^{2}\alpha+tg^{2}\alpha+Ctg^{2}\alpha=2(Sin^{2}\alpha+Cos^{2}\alpha)+(\frac{Sin^{2}\alpha}{Cos^{2}\alpha}+\frac{Cos^{2}\alpha}{Sin^{2}\alpha})=2+\frac{Sin^{4}\alpha+Cos^{4}\alpha}{Sin^{2}\alpha Cos^{2}\alpha}=\frac{Sin^{4}\alpha+2Sin^{2}\alpha Cos^{2}\alpha+Cos^{4}\alpha}{Sin^{2}\alpha Cos^{2}\alpha}=\frac{(Sin^{2}\alpha+Cos^{2}\alpha)^{2}}{Sin^{2}\alpha Cos^{2}\alpha} =\frac{1}{Sin^{2}\alpha Cos^{2}\alpha}$

$\frac{1}{Sin^{2}\alpha Cos^{2}\alpha}=\frac{1}{Sin^{2}\alpha Cos^{2}\alpha}$

Тождество доказано