Update cheatsheet.fr.md

12.temporary_ins/07.geometry-coordinates-prop2/40.n4/20.overview/cheatsheet.fr.md

@@ -1013,10 +1013,11 @@ $`\begin{align}\Large{\color{brown}{\dfrac{d\mathbf{v}}{d\lambda}}}&=\dfrac{d}{d
 &=\dfrac{dv^a}{d\lambda}\,\mathbf{e_a}+v^a\,\dfrac{d\mathbf{e_a}}{d\lambda}\\
 \\
 &=\dfrac{dv^a}{d\lambda}\,\mathbf{e_a}+v^a\,\underbrace{\dfrac{d\mathbf{e_a}}{dx^b}}
-_{\color{brown}{=\,\Gamma_{ab}^{\;c}\,\mathbf{e_c}}}
+_{\color{blue}{=\,\Gamma_{ab}^{\;c}\,\mathbf{e_c}}}
 \,\dfrac{dx^b}{d\lambda}\\
 \\
-&=\dfrac{dv^a}{d\lambda}\,\mathbf{e_a}+v^a\,\dfrac{dx^b}{d\lambda}\,\Gamma_{ab}^{\;c}\,\mathbf{e_c}
+&=\dfrac{dv^a}{d\lambda}\,\mathbf{e_a}+\underbrace{v^a\,\dfrac{dx^b}{d\lambda}\,\Gamma_{ab}^{\;c}\,\mathbf{e_c}}
+_{\color{blue}{\begin{array}{c}\text{a, b et c muets} \,\Longrightarrow \\ \text{interchangeables}\end{array}}
 \end{align}`$