\input{preamble-standalone.ltx} \begin{document} % Ex. No. 245 (Section 31.1.3 : Example 3: extend lines) \begin{tikzpicture} \tkzSetUpLine[add=.5 and .5] \tkzDefPoints{0/0/A,4/0/B,1/3/C} \tkzDrawLines(A,B B,C A,C) \end{tikzpicture} \end{document}