\begin{exercice}Trouver les valeurs de $x$ pour lesquelles le triangle ci-dessous est équilatéral. 
\begin{center}
 \begin{tikzpicture}[general, scale=2.5]
  \draw (0,0)--(0.5,0.87)--(1,0)--cycle; 
  \draw (0.5,0.87)--(0.5,0);
  \draw[shift={(0.5,0)}] (0,0)rectangle (0.15,0.15);
 \draw (0.17, 0.435) node[color=A1, rotate=60] {{\boldmath $2x+7$}}; 
 \draw (0.43, 0.42) node[color=A1, rotate=90] {{\boldmath $5x-4$}}; 
 \end{tikzpicture}
\end{center}

\end{exercice}