Como rotular politopos

Question

Desenhei este politopo, agora quero rotulá-lo com uma letra grega dentro, como faço isso?

\begin{center}
\begin{tikzpicture}[thick,scale=5]
\coordinate (A1) at (5.0,0.2);
\coordinate (A2) at (4.8,0);
\coordinate (A3) at (4.8,-0.3);
\coordinate (A4) at (5.1,-0.5);
\coordinate (A5) at (5.4, -0.15);

\coordinate (B1) at (4.6,0);
\coordinate (B2) at (5.4, 0);

\draw(A1) -- (A2) -- (A3) -- (A4) -- (A5) -- cycle ;
\draw(B1) -- (B2);

\end{tikzpicture}
\end{center}

Answer 1

\documentclass{article}

\usepackage{tikz}

\begin{document}

\begin{center}
\begin{tikzpicture}[thick,scale=5]
\coordinate (A1) at (5.0,0.2);
\coordinate (A2) at (4.8,0);
\coordinate (A3) at (4.8,-0.3);
\coordinate (A4) at (5.1,-0.5);
\coordinate (A5) at (5.4, -0.15);

\coordinate (B1) at (4.6,0);
\coordinate (B2) at (5.4, 0);

\draw (A1) -- (A2) -- (A3) -- (A4) -- (A5) -- cycle ;
\draw (B1) -- (B2);
\path (A1.south) |- (A5.west) node [midway,above] {$\pi$};
% or a cleaner version, as @TorbjørnT. said in the comments:
% \node at (A1.south |- A5.west) {$\pi$};

\end{tikzpicture}
\end{center}

\end{document}