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

% Ex. No. 204 (Section 24.5 : Option \tkzname{R with nodes})

\begin{tikzpicture}
  \tkzDefPoint(0,0){O}
  \tkzDefPoint(2,-1){A}
  \tkzDefPoint(1,1){B}
  \tkzCalcLength(B,A)\tkzGetLength{radius}
  \tkzDrawArc[R with nodes](B,\radius pt)(A,O)
\end{tikzpicture}

\end{document}