tracerepere
40 setxunit
40 setyunit
-3 3 setxrange
-3 3 setyrange
unites
/O {0 0} def
/A {2 0} def
/B {1.73 1} def
/C {-1.73 -1} def
[A B C] points
setTimesItalic
(O) O drtext
(A) A drtext
(B) B drtext
(C) C drtext

[A B C] dashpoints
[A B C] polygone
bleu
O 2  cercle