\input{preamble-standalone.ltx} \begin{document} % Ex. No. 62 (Section 10.1.3 : Option \tkzname{colinear at} with $K=\frac{\sqrt{2}}{2}$) \begin{tikzpicture}[vect/.style={->, shorten >=3pt,>=latex'}] \tkzDefPoint(1,1){A} \tkzDefPoint(4,2){B} \tkzDefPoint(2,2){CU} \tkzDefPointWith[colinear=at C,K=sqrt(2)/2](A,B) \tkzGetPoint{D} \tkzDrawPoints[color=red](A,B,C,D) \tkzDrawSegments[vect](A,B C,D) \end{tikzpicture} \end{document}