\begin{tikzpicture}[>=latex] \tkzDefPoint(1,4){a} \tkzDefPoint(3,2){b} \tkzDefPoint(1,1){c} \tkzDrawSegment[->,red](a,b) \tkzGetPointCoord(c){c} \draw[color=blue,->](a) -- ([shift=(b)]\cx,\cy) ; \draw[color=purple,->](b) -- ([shift=(b)]\cx,\cy) ; \tkzDrawSegment[->,blue](a,c) \tkzDrawSegment[->,purple](b,c) \end{tikzpicture}