-3 3 setxrange
-2 4 setyrange

tracerepere
marks
/A {3 sqrt 1} def
/B {3 sqrt neg 3} def
/G {0 12 9 div} def
/M {0 2} def

[A B] dashpoints
[M G] points
[A O B] polygone

setTimesItalic
   (A) A urtext
   (B) B urtext
   (G) G urtext
   (M) M urtext
   (O) O dltext