Update cheatsheet.fr.md

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

@@ -1391,17 +1391,20 @@ une **valeur moyenne**, et de leurs **écarts respectifs** par rapport à la val
 $`\begin{array}\quad = &A_1\,cos\big(\underbrace{\omega_1 t + \overrightarrow{k}_1\cdot\overrightarrow{r}+\varphi_1}_{\color{blue}{\theta_1(\vec{r},t)}}\big)\\
   &+ A_2\,cos\big(\underbrace{\omega_2 t + \overrightarrow{k}_2\cdot\overrightarrow{r}+\varphi_2}_{\color{blue}{\theta_2(\vec{r},t)}}\big)\end{array}`$
 
-$`\quad\quad = A_1\,cos\,\theta_1 + A_2\,cos\,\theta_2`$   
+$`\quad\;\, = A_1\,cos\,\theta_1 + A_2\,cos\,\theta_2`$   
 
-$`\quad\quad = (A_{moy}+ \Delta A_{1-2})\,cos\,\theta_1 + (A_{moy} - \Delta A_{1-2})\,cos\,\theta_2`$   
+$`\quad\;\, = (A_{moy}+ \Delta A_{1-2})\,cos\,\theta_1 + (A_{moy} - \Delta A_{1-2})\,cos\,\theta_2`$   
 
-**$`\quad\quad = A_{moy}\,(cos\,\theta_1 + cos\,\theta_2) + \Delta A_{1-2}\,(cos\theta_1 - cos\theta_2)`$**
+**$`\quad\;\, = A_{moy}\,(cos\,\theta_1 + cos\,\theta_2) + \Delta A_{1-2}\,(cos\theta_1 - cos\theta_2)`$**
 
 * *Travaillons* les **termes de phase** :
 
+$`\theta_1 = \omega_1 t + \overrightarrow{k}_1\cdot\overrightarrow{r}+\varphi_1`$
 
+$`\quad\;\,= \big[ (\omega_{moy}+ \Delta \omega_{1-2}) t + \big(\overrightarrow{k}_{moy}+ \Delta \overrightarrow{k}_{1-2}\big)\cdot\overrightarrow{r}+( \varphi_{moy} + \Delta \varphi_{1-2})\big]`$
 
-
+$`\quad\;\,= \big[ \big(\omega_{moy} t + \overrightarrow{k}_{moy}\cdot\overrightarrow{r}+ \varphi_{moy}\big)
++ \big(\Delta \omega_{1-2}) t + \Delta \overrightarrow{k}_{1-2}\cdot\overrightarrow{r}+\Delta\varphi_{1-2}\big)\big]`$