Update cheatsheet.fr.md

12.temporary_ins/08.grad-div-rot/20.div/20.overview/cheatsheet.fr.md

@@ -25,6 +25,9 @@ div\,\overrightarrow{X}}\;\color{black}{=\;\dfrac{d\Phi_X}{d\tau}}\;
 <br>**$`div\,\overrightarrow{X}\;=\;\color{gray}{\dfrac{d\Phi_X}{d\tau}}\;=\;\dfrac{\partial X_x}{\partial x}+\dfrac{\partial X_y}{\partial y}+\dfrac{\partial X_z}{\partial z}
 `$**
 
+<br>**$`\mathbf{div\,\overrightarrow{X}\;=\;\color{black}{\dfrac{d\Phi_X}{d\tau}}\;=\;\dfrac{\partial X_x}{\partial x}+\dfrac{\partial X_y}{\partial y}+\dfrac{\partial X_z}{\partial z}
+}`$**
+
 ##### Expression de la divergence en coordonnées cylindriques
 
 <br>**$`\mathbf{div\,\overrightarrow{X}}`$**$`\boldsymbol{\mathbf{\;=\dfrac{d\Phi_X}{d\tau}}}`$**$`\boldsymbol{\mathbf{\;=\dfrac{1}{\rho}\;\dfrac{\partial\,(\,\rho\,X_{\rho})}{\partial\,\rho}
@@ -47,10 +50,10 @@ div\,\overrightarrow{X}\color{grey{\;=\;\dfrac{d\Phi_X}{d\tau}}\,=\; &\dfrac{1}{
 
 <br>
 
-**$`\mathbf{\boldsymbol{\begin{matrix}
+**$`\mathbf{\boldsymbol{\begin{align}
 div\,\overrightarrow{X}\color{gray}{\;=\dfrac{d\Phi_X}{d\tau}}\,= &\dfrac{1}{r^2}\;\dfrac{\partial\,(r^2\,X_r}{\partial\,r}\\
 & \quad\quad + \dfrac{1}{r\,sin\,\theta}\;\dfrac{\partial\,(sin\,\theta\,X_{\theta})}{\partial\,\theta}\\
-& \quad\quad\quad\quad + \dfrac{1}{r\,sin\,\theta}\;\dfrac{\partial\,X_{\varphi}}{\partial\,\varphi}\end{matrix}}}`$**
+& \quad\quad\quad\quad + \dfrac{1}{r\,sin\,\theta}\;\dfrac{\partial\,X_{\varphi}}{\partial\,\varphi}\end{align}}}`$**
 
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