Rieš v \( \mathbb{R}-\left\{\frac{\pi}{2}+\frac{k \pi}{2};k\in\mathbb{Z}\right\} \) rovnicu \( \frac{(\operatorname{tg} x-\operatorname{cotg} x)^{2}}{\operatorname{cotg}^{2} x+\operatorname{tg}^{2} x}+\frac{2}{\operatorname{tg}^{2} x+\operatorname{cotg}^{2} x}=\sin x \)