Update cheatsheet.fr.md

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

@@ -23,6 +23,11 @@ div\,\overrightarrow{X}}`$**$`\mathbf{\;=\dfrac{d\Phi_X}{d\tau}}`$**$`\;\mathbf{
 <br>**$`\mathbf{div\,\overrightarrow{X}}`$**$`\boldsymbol{\mathbf{\;=\dfrac{d\Phi_X}{d\tau}}}`$**$`\boldsymbol{\mathbf{\;=\dfrac{1}{\rho}\;\dfrac{\partial\,(\,\rho\,X_{\rho})}{\partial\,\rho}
 +\dfrac{1}{\rho}\;\dfrac{\partial\,X_{\varphi}}{\partial\,\varphi}+\dfrac{\partial\,X_{z}}{\partial\,z}}}`$**
 
+<br>
+
+<br>**$`div\,\overrightarrow{X}`$**$`\;=\dfrac{d\Phi_X}{d\tau}`$**$`\;=\dfrac{1}{\rho}\;\dfrac{\partial\,(\,\rho\,X_{\rho})}{\partial\,\rho}
++\dfrac{1}{\rho}\;\dfrac{\partial\,X_{\varphi}}{\partial\,\varphi}+\dfrac{\partial\,X_{z}}{\partial\,z}`$**
+
 
 ##### Expression de la divergence en coordonnées sphériques