\input{preamble-standalone.ltx}
\begin{document}

% Ex. No. 157 (Section 19.5.1 : Example)

\begin{tikzpicture}
  \tkzInit[xmax=5,ymax=5]
  \tkzGrid \tkzClip
  \tkzDefPoint(0,0){A}
  \tkzDefPoint(2,2){O}
  \tkzDefPoint(4,4){B}
  \tkzDefPoint(6,6){C}
  \tkzDrawPoints(O,A,B,C)
  \tkzLabelPoints(O,A,B,C)
  \tkzDrawCircle(O,A)
  \tkzClipCircle(O,A)
  \tkzDrawLine(A,C)
  \tkzDrawCircle[fill=red!20,opacity=.5](C,O)
\end{tikzpicture}

\end{document}