Update cheatsheet.fr.md

12.temporary_ins/40.classical-mechanics/20.n2/10.framework-of-classical-mechanics-2/20.overview/cheatsheet.fr.md

@@ -246,8 +246,8 @@ sur les condtions de mesure des durées et des longueurs?
 <span style="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;color:#bbbbbb">appelé 
 </span><span style="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;left;color:#bb3300"> longueur  l<sub>AB</sub>
 </span><span style="font-family:'Times New Roman';font-weight:bold;font-size:0.85rem;color:#6699ff"> entre ces deux points.</span>
-<span style="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;text-align:left;color:#bbbbbb">d'expression</span>
-<span style="font-family:'Times New Roman';font-weight:bold;font-size:0.85rem;text-align:left;color:#009900">$`l_{AB}=\sqrt{(x_B-x_A)^2+(y_B-y_A)^2+(z_B-z_A)^2}`$</span><br>
+<span style="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;text-align:left;color:#bbbbbb">d'expression en coordonnées cartésienne</span></p>
+$`\color{green}{l_{AB}=\sqrt{(x_B-x_A)^2+(y_B-y_A)^2+(z_B-z_A)^2}`$
 <span style="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;text-align:left;color:#bbbbbb">en coordonnées cartésiennes $`(x,y,z)`$</span></p>
 <hr width=100% size=6px border-style="solid" color=#00bb33>
 <p style="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;text-align:left;color:#bbbbbb">un <span style="color:#0066cc"> invariant temporel<br>