[TiKZ] Méthode d’Archimède

\begin{tikzpicture}
  %% CERCLE TRIGONOMETRIQUE
  \draw (0,0) circle (4cm);

  %% CENTRE DU CERCLE
  \fill (0,0) circle (1.5pt);
  \node at (0,0) [anchor=south] {$O$};

  %% HEXAGONE INTERIEUR
  \fill (3.46,0) circle (1.5pt);
  \node at (3.46,0) [anchor=south east] {$I$};
  \fill (3.46,-2) circle (1.5pt);
  \node at (3.46,-2) [anchor=south east] {$A$};
  \fill (3.46,2) circle (1.5pt);
  \node at (3.46,2) [anchor= north east] {$B$};
  \fill (0,4) circle (1.5pt);
  \node at (0,4) [anchor=north] {$C$};
  \fill (-3.46,2) circle (1.5pt);
  \node at (-3.46,2) [anchor=north west] {$D$};
  \fill (-3.46,-2) circle (1.5pt);
  \node at (-3.46,-2) [anchor=south west] {$E$};
  \fill (0,-4) circle (1.5pt);
  \node at (0,-4) [anchor=south] {$F$};
  \draw (3.46,-2) -- (3.46,2) -- (0,4) -- (-3.46,2) -- (-3.46,-2) -- (0,-4) -- cycle;

  %% HEXAGONE EXTERIEUR
  \fill (4,0) circle (1.5pt);
  \node at (4,0) [anchor=west] {$I'$};
  \fill (4,2.31) circle (1.5pt);
  \node at (4,2.31) [anchor=south west] {$B'$};
  \fill (4,-2.31) circle (1.5pt);
  \node at (4,-2.31) [anchor=north west] {$A'$};
  \fill (0,4.62) circle (1.5pt);
  \fill (-4,2.31) circle (1.5pt);
  \fill (-4,-2.31) circle (1.5pt);
  \fill (0,-4.62) circle (1.5pt);
  \draw (4,-2.31) -- (4,2.31) -- (0,4.62) -- (-4,2.31) -- (-4,-2.31) --      (0,-4.62) -- cycle;

  %% TRIANGLES
  \draw (0,0) -- (4,0);
  \draw (0,0) -- (4,-2.31);
  \draw (0,0) -- (4,2.31);
\end{tikzpicture}