\input{preamble-standalone.ltx} \begin{document} % Ex. No. 135 (Section 17.8.1 : \tkzcname{tkzClipPolygon}) \begin{tikzpicture}[scale=1.25] \tkzInit[xmin=0,xmax=4,ymin=0,ymax=3] \tkzClip[space=.5] \tkzDefPoint(0,0){A} \tkzDefPoint(4,0){B} \tkzDefPoint(1,3){C} \tkzDrawPolygon(A,B,C) \tkzDefPoint(0,2){D} \tkzDefPoint(2,0){E} \tkzDrawPoints(D,E) \tkzLabelPoints(D,E) \tkzClipPolygon(A,B,C) \tkzDrawLine[color=red](D,E) \end{tikzpicture} \end{document}