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

% Ex. No. 121 (Section 19.1.4 : Example with the option \tkzimp{ex})

\begin{tikzpicture}[scale=.75]
	\tkzDefPoints{ 0/0/A,4/0/B,0.8/4/C}
	\tkzDefCircle[ex](B,C,A)
  \tkzGetPoint{Jc} \tkzGetLength{rc}
	\tkzDefPointBy[projection=onto A--C ](Jc)
  \tkzGetPoint{Xc}
  \tkzDefPointBy[projection=onto A--B ](Jc)
  \tkzGetPoint{Yc}
  \tkzGetPoint{I}
  \tkzDrawPolygon[color=blue](A,B,C)
  \tkzDrawCircle[R,color=lightgray](Jc,\rc pt)
  % possible  \tkzDrawCircle[ex](A,B,C)
  \tkzDrawCircle[in,color=red](A,B,C)    \tkzGetPoint{I}
	\tkzDefPointBy[projection=onto A--C ](I)
  \tkzGetPoint{F}
	\tkzDefPointBy[projection=onto A--B ](I)
  \tkzGetPoint{D}
	\tkzDrawLines[add=0 and 2.2,dashed](C,A C,B)
	\tkzDrawSegments[dashed](Jc,Xc I,D  I,F Jc,Yc)
	\tkzMarkRightAngles(A,F,I B,D,I Jc,Xc,A Jc,Yc,B)
	\tkzDrawPoints(B,C,A,I,D,F,Xc,Jc,Yc)
 	\tkzLabelPoints(B,A,Jc,I,D,Xc,Yc)
 	\tkzLabelPoints[above left](C)
	\tkzLabelPoints[left](F)
\end{tikzpicture}

\end{document}
