\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}