On considère la figure suivante:
\begin{center}
\begin{tikzpicture}
\draw (0,0) node[below left] {A} -- (4,0) node[below right] {B} -- (5,2) node[above right] {C} -- (1,2) node[above left] {D} -- cycle;
\draw (0,0) -- (5,2) node[midway,above,rotate=30] {6};
\node[below] at (2,0) {4};
\node[below right] at (4.5,1) {3};
\end{tikzpicture}
\end{center}

ABCD est un parallélogramme tel que $AB=4$, $BC=3$ et $AC=6$.

\medskip

Calculer $\prodscal{AB}{AC}$.

