Update cheatsheet.fr.md

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

@@ -244,16 +244,16 @@ sur les condtions de mesure des durées et des longueurs?
 <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 spatial<br>
 <span style="font-family:'Times New Roman';margin-left:30px;font-weight:bold;font-size:0.85rem;text-align:right;color:#6699ff">entre deux points A et B de l'espace </span><br>
 <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 en coordonnées cartésienne</span></p>
+</span><span style="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;left;color:#bb3300"> longueur  l<sub>AB</sub><br>
+</span><span style="font-family:'Times New Roman';font-weight:bold;font-size:0.85rem;color:#6699ff"> entre ces deux points.</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>
 $`\color{green}{l_{AB}=\sqrt{(x_B-x_A)^2+(y_B-y_A)^2+(z_B-z_A)^2}}`$
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 <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>
 <span style="font-family:'Times New Roman';margin-left:30px;font-weight:bold;font-size:0.85rem;text-align:right;color:#6699ff">entre deux instants t<sub>1</sub> et t<sub>2</sub> du temps</span><br>
 <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"> durée  Δt<sub>1 2</sub></sub></span>
-<span style="font-family:'Times New Roman';font-weight:bold;font-size:0.85rem;color:#6699ff"> entre ces deux instants.</span>
+</span><span style="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;left;color:#bb3300"> durée  Δt<sub>1 2</sub></sub></span><br>
+<span style="font-family:'Times New Roman';font-weight:bold;font-size:0.85rem;color:#6699ff"> entre ces deux instants.</span><br>
 <span style="font-family:'Times New Roman';font-weight:bold;font-size:1.15rem;text-align:left;color:#bbbbbb">d'expression</span></p>
 $`\color{green}{\Delta t_{1\,2}=|t_2-t_1|=\sqrt{(t_2-t_1)^2}}`$</p>
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