Update cheatsheet.fr.md

12.temporary_ins/69.waves/20.n2/20.overview/cheatsheet.fr.md

@@ -384,13 +384,13 @@ $`\begin{align}
 \end{align}`$
 
 <br>
-$`(t_2' - t_1')\; (\mathscr{v_{propag.} - \mathscr{v_{capteur})= (t_2 - t_1)\;
-(\mathscr{v_{propag.}- \mathscr{v_{source})`$
+$`(t_2' - t_1')\; (\mathscr{v}_{propag.} - \mathscr{v}_{capteur})= (t_2 - t_1)\;
+(\mathscr{v}_{propag.}- \mathscr{v}_{source})`$
 
 
 <br>
-$`\mathbf{(t_2' - t_1')= (t_2 - t_1)\cdot \dfrac{\mathscr{v}_{propag.}- \mathscr{v}_{source}}
-{\mathscr{v}_{propag.} - \mathscr{v}_{capteur}}} \quad(\text{eq. Dop.6})`$
+$`\boldsymbol{\mathbf{(t_2' - t_1')= (t_2 - t_1)\cdot \dfrac{\mathscr{v}_{propag.}- \mathscr{v}_{source}}
+{\mathscr{v}_{propag.} - \mathscr{v}_{capteur}}}} \quad(\text{eq. Dop.6})`$