Source
%% auteur : 

30 setxunit
30 setyunit
-2.1 2.1 setxrange
-2.1 2.1 setyrange
%tracerepere
/O{0 0} def
/cerc{O 2} def
/A{90 cerc cpoint} def
/B{40 cerc cpoint} def
/C{-10 cerc cpoint} def
/D{-60 cerc cpoint} def
/E{-110 cerc cpoint} def

cerc cercle
[O A B] polygone
[B C D E] ligne
[O C] ligne
B O A .3 (-) tripointarcarrow
O B C .3 (=) tripointarcarrow
C D E .3 (=) tripointarcarrow
C D E .2 (-) tripointarcarrow
[O A O B O C]{2 marked} dapply
[A B B C C D D E]{1 marked} dapply


<tex>
$\alpha$
</tex>
0.3 0.6 cctexlabel

<tex>
$\beta$
</tex>
1.4 0.7 cctexlabel

<tex>
$\gamma$
</tex>
0.65 -1.2 cctexlabel