\input{preamble-standalone.ltx} \begin{document} % Ex. No. 159 (Section 20.1.1 : Example of intersection between two straight lines) \begin{tikzpicture}[rotate=-45,scale=.75] \tkzDefPoint(2,1){A} \tkzDefPoint(6,5){B} \tkzDefPoint(3,6){C} \tkzDefPoint(5,2){D} \tkzDrawLines(A,B C,D) \tkzInterLL(A,B)(C,D) \tkzGetPoint{I} \tkzDrawPoints[color=blue](A,B,C,D) \tkzDrawPoint[color=red](I) \end{tikzpicture} \end{document}