%% auteur : 

-1 5 setxrange
-1 5 setyrange
50 setxunit
50 setyunit
/A{0 4} def
/B{4 4} def
/C{4 0} def
/D{0 0} def
/M{1.5 4} def
/N{4 2.5} def
[A B C D] polygone

A B C angledroit
B C D angledroit
C D A angledroit
D A B angledroit
/fillstyle {.5 setgray continu hachure} def

    mixte [M N D] polygone* 

pointilles
[M N D] polygone
setTimes
(A) A [1.5 1.5] ultext
(B) B [1.5 1.5] urtext
(C) C [1.5 1.5] dtext
(D) D [1.5 1.5] dltext
(M) M [1.5 1.5] utext
(N) N [1.5 1.5] rtext
setTimesItalic
(x) 0.75 4 [1.5 1.5] utext

(x) 4 3.25 [1.5 1.5] rtext