Update cheatsheet.fr.md

10.temporary-m3p2/50.mathematics/20.algebra-analysis/20.n2/20.trigonometry/20.overview/cheatsheet.fr.md

@@ -46,7 +46,7 @@ $`\def\PSclosed{\mathscr{S}_{\displaystyle\tiny\bigcirc}}`$
 <br>
 
 RÉSUMÉ
-: ---   
+:  
   $`cos(a + b) = cos(a)\,cos(b) - sin(a)\,sin(b)`$
 
   $`sin(a + b) = sin(a)\,cos(b) + cos(a)\,sin(b)`$
@@ -55,10 +55,14 @@ RÉSUMÉ
 
   $`sin(a - b) = sin(a)\,cos(b) - cos(a)\,sin(b)`$
   
+  ---
+
   $`cos(a) + \cos(b) = 2 cos\left(\dfrac{a + b}{2}\right) cos\left(\dfrac{a - b}{2}\right)`$
 
   $`sin(a) + \sin(b) = 2 sin\left(\dfrac{a + b}{2}\right) cos\left(\dfrac{a - b}{2}\right)`$
   
+  ---
+
   $`cos(a)\,cos(b) = \dfrac{1}{2} [cos(a + b) + cos(a - b)]`$
 
   $`sin(a)\,sin(b) = \dfrac{1}{2} [cos(a - b) - cos(a + b)]`$