\begin{exercice}
Même consigne qu'à l'exercice \RefExercice{2G6_lireabscurv}.

 \begin{tikzpicture}[general,scale=1.71]
  \draw (0,0) circle (1);
  \draw[dashed] (1,0)--(-1,0);
  \draw[dashed] (0,1)--(0,-1);
  \draw (0.5,0.87)--(-0.5,-0.87);
 \draw (0.5,0.87) node[above right] {$A$};
  \draw (-0.5,0.87) node[above left] {$B$};
  \draw (-1,0) node[left] {$C$};
  \draw (-0.5,-0.87) node[below left] {$D$};
  \draw (0,0)--(-0.5,0.87);
  \draw(0.1,-0.2) node {$O$};
  \draw[color=F1] (0.3,0) arc (0:60:0.3);
  \draw[color=F1] (0,0.3) arc (90:120:0.3);
  \draw[color=F1] (0.4,0.25) node{\bfseries 60\degre};
  \draw[color=F1] (-0.1,0.5) node{\bfseries 30\degre};
 \end{tikzpicture}
 \hfill
 \begin{tikzpicture}[general,scale=1.71]
  \draw (0,0) circle (1);
  \draw (0.71,0.71)--(-0.71,-0.71);
  \draw (-0.71,0.71)--(0.71,-0.71); 
  \draw (0.71,0.71) node[right] {$A$};
  \draw (-0.71,-0.71) node[left] {$B$};
  \draw (-0.71,0.71) node[left] {$C$};
  \draw (0.71,-0.71) node[right] {$D$};
  \draw (0.15,0.15)--(0,0.3)--(-0.15,0.15);
  \draw(0,-0.2) node {$O$};
  \draw (-0.5,-0.87) node[below left] {$\phantom{D}$};
  \draw (0.71,0.71)--(0.71,-0.71);
  \draw (-1,0)--(1,0);
  \draw (0.71,0.355) node[color=C1] {{\boldmath $\approx$}};
  \draw (0.71,-0.355) node[color=C1] {{\boldmath $\approx$}};
 \end{tikzpicture}
\end{exercice}
