Update textbook.fr.md

00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/40.classical-mechanics/10.main/textbook.fr.md

@@ -206,6 +206,13 @@ Partícula :
 
 
 <br>
+
+$`\overrightarrow{L}=\begin{vmatrix}
+\widehat{i} & \widehat{j} & \widehat{k}\\
+x & y & z\\
+p_x & p_y & p_z\end{vmatrix}`$
+
+
 $`\overrightarrow{L}=\begin{vmatrix}
 \hat{i} & \hat{j} & \hat{k}\\
 x & y & z\\