# Writting a Circle in a Latex Document

1. Oct 18, 2009

### EngWiPy

Hello,

I have the following Latex segment of code:

Code (Text):
\documentclass[a4paper,12pt,openany,oneside]{memoir}
\usepackage{tikz}
\begin{document}

\begin{figure}
\begin{center}
\begin{tikzpicture}

\pgfsetfillopacity{0.5}

\draw [very thick,dashed,fill=gray!60](0,0) circle (3.6cm);
\draw [dashed,fill=gray!20](3,2) circle (3.6cm);
\draw (0,0) circle (6cm);

\node (source) at (0,0) [circle,draw] {$S$};
\node (relay) at (3,2) [circle,draw] {$R$};
\node (destination) at (6,0) [circle,draw] {$D$};

\draw [->] (source.60) to node [auto] {} (relay.west);
\draw [->] (relay.east) to node [auto] {} (destination.120);
\draw [->] (source.east) to node [auto,swap] {} (destination.west);

\end{tikzpicture}

\end{center}
\end{figure}
\end{document}
I want to write above each circle. How can I do that?