autocrop
/A {0 0} def
/B {-2 -4} def
/C {2 -4} def

/I {.7 A C ABpoint} def

[A B C] polygone
/dotscale {.7 dup} def
I point

1 setlinewidth
-3.1 -1 atan -3.1 1 atan A 5 (->) Cercle

setTimesItalic
   (A) A uctext
   (B) B dltext
   (C) C drtext
   (I) I brtext