\begin{minipage}{6cm}
\begin{tikzpicture}
\draw (0,0) node[below left] {A} -- (3,0) node[below right] {O} node[midway,below] {30 m} -- (0,4) node[above] {C} -- (0,0);
\draw (0,3) node[left] {B} -- (3,0);
\draw[<->,>=latex] (-0.5,0) -- (-0.5,3) node[midway,left] {15 m};
\draw[<->,>=latex] (-0.5,3) -- (-0.5,4) node[midway,left] {5 m};
\end{tikzpicture}
\end{minipage}
\begin{minipage}{\dimexpr\linewidth-8cm}
\begin{enumerate}
\item Montrer que $\prodscal{OB}{OC}=\rm OA^2+AB\times AC$.
\item Calculer \angle{BOC}.
\end{enumerate}

\vspace*{4cm}
\end{minipage}

