\begin{tikzpicture}
 \tkzDefPoint(0,0){O}
 \tkzDefPoint(1,1){A}
 \tkzDefPoint(4,2){B}
 \tkzGetVectxy(A,B){v}
 \tkzDefPoint(\vx,\vy){V}
 \tkzDrawSegment[->,color=red](O,V)
 \tkzDrawSegment[->,color=blue](A,B)
 \tkzDrawPoints(A,B,O)
 \tkzLabelPoints(A,B,O,V)
\end{tikzpicture}
