Update cheatsheet.fr.md

12.temporary_ins/69.waves/30.n3/20.overview/cheatsheet.fr.md

@@ -1655,7 +1655,7 @@ $`\quad\quad \;\; = \cdots`$
   <br>
   $`\quad\;\; \color{blue}{\scriptsize{exp\,(a+b)\,=\, exp\,a\,+\, exp\,b}}`$  
   <br>
-  $`\quad\;\; = e^{\,i\,\theta_{moy}}\,e^{\,i\,\theta_{12}}\,+\,e^{\,i\,\theta_{moy}}\,e^{-\,i\,\theta_{12}}   
+  $`\quad\;\; = e^{\,i\,\theta_{moy}}\,e^{\,i\,\theta_{12}}\,+\,e^{\,i\,\theta_{moy}}\,e^{-\,i\,\theta_{12}}`$   
   <br>
   $`\quad\;\; = e^{\,i\,\theta_{moy}}\,\big(e^{\,i\,\theta_{12}}\,+\,e^{-\,i\,\theta_{12}}\big)`$   
   <br>