Question

sinx/(1-cosx)-(1+cosx)/sinx

Answer 1

   
[tex]\displaystyle \\ \texttt{Folosim formula:} \\ \\ \text{ctg} \frac{x}{2} = \frac{\sin x}{1-\cos x} = \frac{1+\cos x}{\sin x} \\ \\ \\ \Longrightarrow ~~~\frac{\sin x}{1-\cos x} - \frac{1+\cos x}{\sin x} = \text{ctg} \frac{x}{2} - \text{ctg} \frac{x}{2} = \boxed{0}[/tex]