On considère la configuration suivante.

\begin{center}
 \psset{xunit=0.9cm,yunit=0.9cm}
\begin{pspicture*}(1.64,0.78)(8.1,7.16)
\psgrid[subgriddiv=0,gridlabels=0,gridcolor=CyanTikz40](0,0)(1.64,0.78)(8.1,7.16)
\psset{xunit=0.9cm,yunit=0.9cm,algebraic=true,dotstyle=o,dotsize=3pt 0,linewidth=0.3mm,arrowsize=3pt 2,arrowinset=0.25}
\psaxes[labelFontSize=\scriptstyle,xAxis=true,yAxis=true,Dx=1,Dy=1,ticksize=-2pt 0,subticks=2]{->}(0,0)(1.64,0.78)(8.56,7.16)
\psline[linecolor=A1,linewidth=1.2pt]{->}(7,3)(5,5)
\rput[tl](5.5,4.82){$\vv{u}$}
\psdots[dotstyle=*](3,2)
\rput[bl](2.62,2.04){$A$}
\psdots[dotstyle=*](6,2)
\rput[bl](6.08,2.12){$B$}
\psdots[dotstyle=*](4,4)
\rput[bl](4.08,4.12){$C$}
\psdots[dotstyle=*](7,6)
\rput[bl](7.08,6.12){$D$}
\end{pspicture*}

\end{center}


\begin{exercice} Les coordonnées du vecteur $\vv{u}$ dans le repère $\left(A\ ;\ \vv{BD},\vv{BA}\right)$ sont :

 \begin{ChoixQCM}{4}
    \item $\covec{1/2}{5/6}$
	\item $\covec{1/2}{-5/6}$
    \item $\covec{-2}{-2}$
	\item $\covec{1/2}{-2,5}$
 \end{ChoixQCM}
 \begin{corrige}
      \reponseQCM{a}
    \end{corrige}
    \end{exercice}