-1 9 setxrange
-4 5 setyrange

/A {0 0} def
/B {5 0} def
/C {5 -3} def
/D {0 -3} def
/E {8 -3} def
/F {B A 60 rotatepoint} def
/H {A B milieu} def

A B C D E F H 7 points
A B C D 4 tracepolygone
C E B F A 5 traceligne

setTimesItalic
   (A) A uplefttext
   (B) B uprighttext
   (C) C downrighttext
   (D) D downlefttext
   (E) E downrighttext
   (F) F uptext
   (H) H uprighttext