Срочно!!!1\cos^2x=2tg^2x

[latex]\frac{1}{cos^2(x)} = 2tg^2(x) <=> 1 + tg^2(x) = 2tg^2(x) <=> tg^2(x) = 1 <=>\\ <=> tg(x) = 1;\\ \\ x = \left[\begin{array}{c} arctg(1) + 2\pi k\\ \pi + arctg(1) + 2\pi n\end{array}\right \ k,n \in \mathbb Z\\ \\ x = \left[\begin{array}{c} \frac{\pi}{4} + 2\pi k\\ \frac{5\pi}{4} + 2\pi n\end{array}\right \ k,n \in \mathbb Z [/latex]