diff --git a/01.curriculum/01.physics-chemistry-biology/03.Niv3/02.Geometrical-optics/02.geometrical-optics-foundings/03.optical_path/02.optical-path-overview/textbook.en.md b/01.curriculum/01.physics-chemistry-biology/03.Niv3/02.Geometrical-optics/02.geometrical-optics-foundings/03.optical_path/02.optical-path-overview/textbook.en.md
index 4503b8a44..58ddc5c89 100644
--- a/01.curriculum/01.physics-chemistry-biology/03.Niv3/02.Geometrical-optics/02.geometrical-optics-foundings/03.optical_path/02.optical-path-overview/textbook.en.md
+++ b/01.curriculum/01.physics-chemistry-biology/03.Niv3/02.Geometrical-optics/02.geometrical-optics-foundings/03.optical_path/02.optical-path-overview/textbook.en.md
@@ -42,8 +42,8 @@ de la nature :
 
 **$`\mathrm{d}\delta\;=\;d\dfrac{ds}{c}`$**
 
-$`\delta = \disoplaystyle\int_{S_{AB}}n\cdot\mathrm{d}s\;=\;\int_{S_{AB}}\dfrac{c}{v}\cdot\mathrm{d}s`$
-$`\hspace{1cm}= c\;\int_{S_{AB}}\dfrac{\mathrm{d}s}{v} =\;c\;\tau`$</strong>
+$`\delta=\displaystyle\int_{S_{AB}}n\cdot\mathrm{d}s\;=\;\int_{S_{AB}}\dfrac{c}{v}\cdot\mathrm{d}s`$
+$`\hspace{1cm}=c\;\int_{S_{AB}}\dfrac{\mathrm{d}s}{v}=\;c\;\tau`$</strong>
 
 
 !!! Je peux maintenant considérer un rayon lumineux se propageant d'un point A à un point B,