Update cheatsheet.fr.md

12.temporary_ins/69.waves/30.n3/20.overview/cheatsheet.fr.md

@@ -1401,10 +1401,11 @@ $`\quad\;\, = (A_{moy}+ \Delta A_{1-2})\,cos\,\theta_1 + (A_{moy} - \Delta A_{1-
 
 $`\theta_1 = \omega_1 t + \overrightarrow{k}_1\cdot\overrightarrow{r}+\varphi_1`$
 
-$`\quad\;\,= \big[ (\omega_{moy}+ \Delta \omega_{1-2}) t + \big(\overrightarrow{k}_{moy}+ \Delta \overrightarrow{k}_{1-2}\big)\cdot\overrightarrow{r}+( \varphi_{moy} + \Delta \varphi_{1-2})\big]`$
+$`\begin{align}\quad\;\,= \big[ (\omega_{moy}&+ \Delta \omega_{1-2}) t + \big(\overrightarrow{k}_{moy}+ \Delta \overrightarrow{k}_{1-2}\big)\cdot\overrightarrow{r}\\
+&+( \varphi_{moy} + \Delta \varphi_{1-2})\big]\end{align}`$
 
-$`\quad\;\,= \big[ \big(\omega_{moy} t + \overrightarrow{k}_{moy}\cdot\overrightarrow{r}+ \varphi_{moy}\big)
-+ \big(\Delta \omega_{1-2}) t + \Delta \overrightarrow{k}_{1-2}\cdot\overrightarrow{r}+\Delta\varphi_{1-2}\big)\big]`$
+$`\begin{align}\quad\;\,= \big[ \big(\omega_{moy} t &+ \overrightarrow{k}_{moy}\cdot\overrightarrow{r}+ \varphi_{moy}\big) \\
+&+ \big(\Delta \omega_{1-2}) t + \Delta \overrightarrow{k}_{1-2}\cdot\overrightarrow{r}+\Delta\varphi_{1-2}\big)\big]\end{align}`$