%% auteur : Florent Braisaz

-5 5 setxrange
-5 5 setyrange
15 setxunit
15 setyunit
/cerc{O 4} def
cerc cercle

/A {-130 cerc cpoint} def
/B {-70 cerc cpoint} def

/M {160 cerc cpoint} def
/N {80 cerc cpoint} def

1.25 setlinewidth

[O A] ligne
[O B] ligne

gsave
bleu
[M A] ligne
[M B] ligne
[N A] ligne
[N B] ligne
A M B 1 (-) tripointarc
A N B 1 (-) tripointarc
grestore

gsave
rouge
O A B arcp
A O B 1 (=) tripointarc
grestore

gsave
setTimesItalic
(A) A [1.5 1.5] dltext
(B) B [1.5 1.5] drtext
(M) M [1.5 1.5] cltext
(N) N [1.5 1.5] uctext
(O) O [1.5 1.5] uctext
grestore

#latex# ${\mathcal{C}}$ 
3.5 2 [1.5 dup] crtexlabel