diff --git a/12.temporary_ins/70.wave-optics/20.diffraction/cheatsheet.fr.md b/12.temporary_ins/70.wave-optics/20.diffraction/cheatsheet.fr.md
index e76f0d182..42eca7dac 100644
--- a/12.temporary_ins/70.wave-optics/20.diffraction/cheatsheet.fr.md
+++ b/12.temporary_ins/70.wave-optics/20.diffraction/cheatsheet.fr.md
@@ -212,7 +212,8 @@ $`\displaystyle=\int_{-x_0/2}^{+x_0/2}  e^{\dfrac{i\,2\,\pi\,u_x\,x}{\lambda}}\;
 
 $`\displaystyle \underline{A}=\dfrac{\lambda}{i\,2\,\pi\,u_x}\left(e^{\dfrac{i\,\pi\,u_x\,x_0}{\lambda}}-\;e^{\dfrac{-i\,\pi\,u_x\,x_0}{\lambda}}\right)`$
 
-$`\displaystyle \underline{A}=-i\; \dfrac{\lambda}{i\,2\,\pi\,u_x}\left[ \left(cos\;\dfrac{\pi\,u_x\,x_0}{\lambda}+i\;sin\dfrac{\pi\,u_x\,x_0}{\lambda}\right)\right.`$$`\left.-\left( cos\;\dfrac{\pi\,u_x\,x_0}{\lambda}-i\;sin\;\dfrac{\pi\,u_x\,x_0}{\lambda}\right)\right]`$
+$`\displaystyle \underline{A}=-i\; \dfrac{\lambda}{i\,2\,\pi\,u_x}\left[ \left(cos\;\dfrac{\pi\,u_x\,x_0}{\lambda}`$
+$`\;+i\;sin\dfrac{\pi\,u_x\,x_0}{\lambda}\right)\right.`$$`\left.-\left( cos\;\dfrac{\pi\,u_x\,x_0}{\lambda}-i\;sin\;\dfrac{\pi\,u_x\,x_0}{\lambda}\right)\right]`$
 
 $`\displaystyle \underline{A}=-i\; \dfrac{\lambda}{2\pi,u_x} \left( 2\,sin \;\dfrac{\pi\,u_x\,x_0}{\lambda}\right)`$