From a752601717ae09b84924990bf5df132ca752605c Mon Sep 17 00:00:00 2001
From: Claude Meny <claude.meny@irap.omp.eu>
Date: Sun, 30 Aug 2020 11:08:35 +0200
Subject: [PATCH] Update textbook.fr.md

---
 .../04.reference-frames-coordinate-systems/textbook.fr.md   | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/04.reference-frames-coordinate-systems/textbook.fr.md b/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/04.reference-frames-coordinate-systems/textbook.fr.md
index 939a69fcf..9a939e5e4 100644
--- a/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/04.reference-frames-coordinate-systems/textbook.fr.md
+++ b/00.brainstorming-pedagogical-teams/40.collection-existing-pedagogical-content/04.reference-frames-coordinate-systems/textbook.fr.md
@@ -243,17 +243,17 @@ $`\quad\overrightarrow{dS}\quad`$,$`\quad\overrightarrow{d^2S}\quad`$
 [FR] et les **éléments vectoriels de surface $`\overrightarrow{dA}`$** correspondants sont :<br>
 [EN] and the corresponding **vector surface elements $`\overrightarrow{dA}`$** are :<br>
 <br>$`d\overrightarrow{A_{xy}}=\pm\;\partial\overrightarrow{OM}_x\land\partial\overrightarrow{OM}_y`$
-$`\pm\;\overrightarrow{dl_x}\land\overrightarrow{dl_y}`$
+$`=\pm\;\overrightarrow{dl_x}\land\overrightarrow{dl_y}`$
 $`=\pm\; (dl_x\;\overrightarrow{e_x})\land(dl_y\;\overrightarrow{e_y})`$
 $`=\pm\; dl_x\;dl_y\;(\overrightarrow{e_x}\land\overrightarrow{e_y})`$
 $`= \pm \; dx\;dy\;\overrightarrow{e_z}`$<br>
 <br>$`d\overrightarrow{A_{xz}}=\pm\;\partial\overrightarrow{OM}_x\land\partial\overrightarrow{OM}_z`$
-$`\pm\;\overrightarrow{dl_x}\land\overrightarrow{dl_z}`$
+$`=\pm\;\overrightarrow{dl_x}\land\overrightarrow{dl_z}`$
 $`=\pm\; (dl_x\;\overrightarrow{e_x})\land(dl_z\;\overrightarrow{e_z})`$
 $`=\pm\; dl_x\;dl_z\;(\overrightarrow{e_x}\land\overrightarrow{e_z})`$
 $`=\mp\; dx\;dy\;\overrightarrow{e_z}`$<br>
 <br>$`d\overrightarrow{A_{yz}}=\pm\;\partial\overrightarrow{OM}_y\land\partial\overrightarrow{OM}_z`$
-$`\pm\;\overrightarrow{dl_y}\land\overrightarrow{dl_z}`$
+$`=\pm\;\overrightarrow{dl_y}\land\overrightarrow{dl_z}`$
 $`=\pm\; (dl_y\;\overrightarrow{e_y})\land(dl_z\;\overrightarrow{e_z})`$
 $`=\pm\; dl_y\;dl_z\;(\overrightarrow{e_y}\land\overrightarrow{e_z})`$
 $`=\pm\; dy\;dz\;\overrightarrow{e_x}`$<br>