Update cheatsheet.fr.md

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

@@ -593,7 +593,7 @@ $`\quad\boldsymbol{\mathbf{=\color{brown}{2\,A\cdot cos\Big(\dfrac{\varphi_1-\va
   
 * Calcul de l'onde complexe résultante :  
   <br>
-  $`\mathbf{\underline{U}(x,t)}`$$`\; = \underline{U_1}(x,t) + \underline{U_2}(x,t)`$    
+  **$`\mathbf{\underline{U}(x,t)}`$**$`\; = \underline{U_1}(x,t) + \underline{U_2}(x,t)`$    
   <br>
   $`\quad =A\;\big[ \,e^{\,i\;(kx - \omega t+ \varphi_1)} + e^{\,i\;(kx - \omega t+ \varphi_2)}\,\big]`$     
   <br>
@@ -601,7 +601,7 @@ $`\quad\boldsymbol{\mathbf{=\color{brown}{2\,A\cdot cos\Big(\dfrac{\varphi_1-\va
   <br>
   $`\quad =A\;\big[ \,e^{\,i\;(\alpha + \varphi_1)} + e^{\,i\;(\alpha + \varphi_2)}\,\big]`$
   <br>
-  $`\color{blue}{\scriptsize{\quad\text{Rappel : }e^{\,i\;(a+b)}\;=\;e^{\,i\,a}\timese^{\,i\,b}`$   
+  $`\color{blue}{\scriptsize{\quad\text{Rappel : } e^{\,i\;(a+b)}\;=\;e^{\,i\,a}\times e^{\,i\,b}`$   
   <br>
   $`\quad =A\;\big[ \,e^{\,i\,\alpha}\;e^{\,i\,\varphi_1}\; + \; e^{\,i\,\alpha}\;e^{\,i\,\varphi_2}\,\big]`$   
   $`\quad =A\;e^{\,i\,\alpha}\;\big[\,e^{\,i\,\varphi_1}\; + \; e^{\,i\,\varphi_2}\,\big]`$    
@@ -615,6 +615,8 @@ $`\quad\boldsymbol{\mathbf{=\color{brown}{2\,A\cdot cos\Big(\dfrac{\varphi_1-\va
 
 
 
+
+