\begin{exercice*}
Les deux courbes suivantes ont une équation du type $y=a\sin \omega x$.
Retrouver $a$ et $\omega$ dans chaque cas.
\begin{center}
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\begin{pspicture*}(-6.7,-2.4)(6.7,2.4)
\psgrid[xunit=0.9424778cm,subgriddiv=2,subgridcolor=A3,gridcolor=A3, gridlabels=0pt](0,0)(-6,-3)(5,3)
\psaxes[xunit=0.9424778cm,labelFontSize=\normalsize,xAxis=true,yAxis=true,Dx=1.,Dy=1,ticksize=-2pt]{->}(0,0)(-5,-2.4)(4.26,2.4)
\psplot[linestyle=solid,linewidth=0.8pt,linecolor=red,plotpoints=5000]{-7}{7}{0.5*sin(2*x)}
\psplot[linestyle=solid,linewidth=0.8pt,linecolor=blue!60!black,plotpoints=5000]{-7}{7}{2*sin(0.5*x)}
\uput[u](-2.356,0.4){\textcolor{red}{$\mathscr{C}$}}
\uput[u](3.25,1){\textcolor{blue!60!black}{$\mathscr{C}'$}}
\rput[0](6.6,0.4){\textcolor{Blanc}{$\blacksquare$}}
\rput[0](6.6,0.4){$x$}
\uput[r](0,2){$y$}
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\end{center}
  \begin{corrige}
$\mathscr{C}:y=\tfrac{1}{2}\sin x$.\\
$\mathscr{C}':y=2\sin \tfrac{1}{4}x$.
\end{corrige}
\end{exercice*}

