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

% Ex. No. 122 (Section 16.0.7 : Option   \tkzname{tangential})

\begin{tikzpicture}[scale=.5,rotate=80]
  \tkzDefPoints{0/0/A,6/0/B,1.8/4/C}
  \tkzDefSpcTriangle[tangential,
    name=T](A,B,C){_a,_b,_c}
  \tkzDrawPolygon[red](A,B,C)
  \tkzDrawPolygon[blue](T_a,T_b,T_c)
  \tkzDrawPoints[red](A,B,C)
  \tkzDrawPoints[blue](T_a,T_b,T_c)
  \tkzDefCircle[circum](A,B,C)
  \tkzGetPoint{O}
  \tkzDrawCircle(O,A)
  \tkzLabelPoints[red](A,B,C)
  \tkzLabelPoints[blue](T_a,T_b,T_c)
\end{tikzpicture}

\end{document}