This is LaTeX code:
[latex]
\frac{1}{2^{n+1}}\dfrac{\cot^2{\frac{x}{2^{n+1}}}-1}{\cot{\frac{x}{2^{n+1}}}}+\frac{1}{2^{n+1}}\dfrac{1}{\cot{\frac{x}{2^{n+1}}}}= \frac{1}{2^{n+1}}\dfrac{\cot^2{\frac{x}{2^{n+1}}}}{\cot{\frac{x}{2^{n+1}}}}=\frac{1}{2^{n+1}}\cot{\frac{x}{2^{n+1}}}
[/latex]