diff --git a/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/05.classical-mechanics/vector-analysis/textbook.fr.md b/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/05.classical-mechanics/vector-analysis/textbook.fr.md
index ac682d481..0249b72c7 100644
--- a/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/05.classical-mechanics/vector-analysis/textbook.fr.md
+++ b/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/05.classical-mechanics/vector-analysis/textbook.fr.md
@@ -286,7 +286,11 @@ $`\forall \overrightarrow{V}\in\mathcal{P}\quad\overrightarrow{V}=V_a\cdot\overr
 $`\overrightarrow{U}\cdot\overrightarrow{V}=(U_a\cdot\overrightarrow{a}+U_b\cdot\overrightarrow{b})\cdot (V_a\cdot\overrightarrow{a}+V_b\cdot\overrightarrow{b})`$<br>
 $` = U_a^2\,(\overrightarrow{a}\cdot\overrightarrow{a})+U_a\,V_b\,(\overrightarrow{a}\cdot \overrightarrow{b})`$
 $`+U_b\,V_a\,(\overrightarrow{b}\cdot \overrightarrow{a})+V_b^2\,(\overrightarrow{b}\cdot\overrightarrow{b})`$<br>
-$`\quad = U_a^2\,\overrightarrow{a}^2 + V_b^2\,\overrightarrow{b}^2 + (U_a\,V_a+U_b\,V_a)\,(\overrightarrow{a}\cdot \overrightarrow{b})`$
+$`= U_a^2\,\overrightarrow{a}^2 + V_b^2\,\overrightarrow{b}^2 + (U_a\,V_a+U_b\,V_a)\,(\overrightarrow{a}\cdot \overrightarrow{b})`$
+
+##### Norma de un vector / norme d'un vecteur / ...
+
+$`||\overrightarrow{U}||=\sqrt{\overrightarrow{U}\cdot\overrightarrow{U}}=\overrightarrow{U}^{\dfrac{1}{2}}`$
 
 
 ##### Vector unitario / Vecteur unitaire /