= \frac{1 - \sqrt{\sin x}}{1 + \sqrt{\sin x}} \cdot \frac{(1 - \sqrt {\sin x} ) \cdot \frac{\cos x}{2 \cdot \sqrt{\sin x}} + \frac{\cos x}{2 \cdot \sqrt{\sin x}} \cdot (1 + \sqrt {\sin x})}{(1 - \sqrt{\sin x})^2} + 2 \cdot \frac {\cos x}{(1 + \sin x) \cdot 2 \cdot \sqrt {\sin x}}