28.45 setxunit
-1 7 setxrange
-1 4 setyrange

/O {0 0} def
/I {5 0} def
/J {6 3} def
/K {1 3} def


/A {O O I vecteur 0.5 mulv translatepoint} def
/B {O O K vecteur 1 3 div mulv translatepoint} def
/G {A A B vecteur 3 5 div mulv translatepoint} def
[O I J K O] ligne
(A) A [1.5 dup ] dctext
(B) B [1.5 dup ] bltext
(O) O [1.5 dup ] dltext
(I) I [1.5 dup ] drtext 
(J) J [1.5 dup ] urtext
(K) K [1.5 dup ] ultext
(G) G [1.5 dup ] uctext
A G 5 Arc
[A B] ligne
[O J ] pointilles ligne
O A 2 marked
A I 2 marked


%[O I J K] {plus3} papply