\begin{tikzpicture} \tkzDefPoints{-1.5/-0.25/A,1/-0.75/B,-1.5/2/C} \tkzDrawLine(A,B) \tkzDefLine[parallel=through C](A,B) \tkzGetPoint{c} \tkzShowLine[parallel=through C](A,B) \tkzDrawLine(C,c) \tkzDrawPoints(A,B,C,c) \end{tikzpicture}