\begin{tikzpicture}
  \foreach \theta in {0, 36, ..., 324} {
    \pgfmathtruncatemacro{\phi}{\theta-90};
    \draw (\theta:0.7) -- ++(\phi:0.5);
  };
  \foreach \theta in {0, 18, ..., 342} {
    \pgfmathtruncatemacro{\phi}{\theta-90};
    \draw (\theta:1.25) -- ++(\phi:0.5);
  };
  \foreach \theta in {0, 12, ..., 348} {
    \pgfmathtruncatemacro{\phi}{\theta-90};
    \draw (\theta:1.75) -- ++(\phi:0.5);
  };
  \node[circle,inner sep=0,minimum width=0.7cm,draw=black,fill=black!20] at (0,0) {};
\end{tikzpicture}
