\[f(n) = 2n\cos\frac{\tau}{2n}\tan\frac{\tau}{2n}\] \[\lim_{n\rightarrow\infty} f(n) = \tau\] \begin{itemize} % must be in paragraph mode \item $\tau_{4} = 4\sqrt{2}$ \item $\tau_{6} = 6$ \item $\tau_{8} = 8\sqrt{2 - \sqrt{2}}$ \end{itemize}