\solution{13.1}{corriges/exercice-13.1.tex}
\solution{13.2}{corriges/exercice-13.2.tex}
\solution{13.3}{corriges/exercice-13.3.tex}
\solution{13.4}{corriges/exercice-13.4.tex}
\solution{13.5}{corriges/exercice-13.5.tex}
\solution{13.6}{corriges/exercice-13.6.tex}
\solution{13.7}{corriges/exercice-13.7.tex}
\solution{13.8}{corriges/exercice-13.8.tex}
\solution{13.9}{corriges/exercice-13.9.tex}