Update textbook.fr.md

00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/05.classical-mechanics/vector-analysis/textbook.fr.md

@@ -305,8 +305,9 @@ $`\quad\Longleftrightarrow\quad cos(\widehat{\overrightarrow{U},\overrightarrow{
 "$`\overrightarrow{U}`$ et $`\overrightarrow{V}`$ sont colinéaires"
 $`\quad\Longrightarrow\quad ...`$
 
-$` \underline{\overrightarrow{B}}^{\,0}_{\,inc}=\left|\begin{array}{l} -\,B_{inc}^0\,cos\,\theta_{inc} \\ 0 
-\\ +\,B_{inc}^0\,sin\,\theta_{inc} \end{array}\right. \quad , \quad`$ 
+"$`\overrightarrow{U}`$ et $`\overrightarrow{V}`$ sont colinéaires"`$
+$`\Longrightarrow\left|\overrightarrow{U}\cdot\overrightarrow{V}=+||\overrightarrow{U}||\cdot||\overrightarrow{V}||\,si\,\widehat{\overrightarrow{U},\overrightarrow{V}}=0\\ 
+\overrightarrow{U}\cdot\overrightarrow{V}=-||\overrightarrow{U}||\cdot||\overrightarrow{V}||\,si\, \widehat{\overrightarrow{U},\overrightarrow{V}}=\pi`$ 
 
 $` \underline{\overrightarrow{B}}^{\,0}_{\,ref}=\left|\begin{array}{l} +\,B_{ref}^0\,cos\,\theta_{ref} \\ 0 
 \\ +\,B_{ref}^0\,sin\,\theta_{ref} \end{array}\right.\quad , \quad `$