autocrop
20 setxunit
%quadrillage marks
-15 17 setxrange
-2 13 setyrange
/l 8 def

/a {0 l l} def    
/b {l l l} def    
/c {l 0 l} def    
/d {0 0 l} def    
/e {0 l 0} def 
/f {l l 0} def
/g {l 0 0} def
/h {0 0 0} def
/i {1.5 6.5 l} def
/j {6.5 0 4.5} def
/k {6 4 l} def

/vect_I {-5 cos -5 sin} def
/vect_J {35 cos 35 sin .6 mulv} def
/vect_K {0 1} def

%% [O vect_I] (->) ligne
%% [O vect_J] (->) ligne
%% [O vect_K] (->) ligne

/xyz2xy {
3 dict begin
   /z exch def
   /y exch def
   /x exch def
   vect_I x mulv
   vect_J y mulv
   vect_K z mulv
   addv addv
end
} def

[/A /B /C /D /E /F /G /H /I /J /K] 
[a b c d e f g h i j k] {xyz2xy} capply
mapnp
ymax I J K paral ydpoint /K' defpoint


%% corrige
I K D C interdroite
/U defpoint
I K B C interdroite
/V defpoint
J U C G interdroite
/W defpoint
I K A D interdroite
/U' defpoint
V W U' paral D H interdroite
/V' defpoint

/fillstyle {.9 setgray fill} def
gsave
.6 setlinewidth
mixte
[U' V' W V] polygone*
pointilles
orange
[W U V] ligne
grestore
[U] {times2} plot
%%%%%%%%%%

/dotscale {2 dup} def
1.2 setlinewidth
[A B C G F B] ligne
[C D A] ligne
[D H G] ligne

gsave
   .8 setlinewidth
   pointilles
   [A E H] ligne
   [E F] ligne
grestore

[I J K] {times} plot

12 setfontsize
setTimesItalic
   (A) A ultext   
   (B) B urtext	  
   (C) C dltext	  
   (D) D dltext	  
   (E) E bltext
   (F) F urtext   
   (G) G drtext   
   (H) H dltext   
   (I) I dltext   
   (J) J (-5 0) cltext   
   (K) K dltext