%% auteur : gh

50 setxunit
-6 6 setxrange
-2.5 5.5 setyrange

/u1 {1 0.3} def
/u2 {-1 1} def
/horiz1 {1 0} def
/horiz2 {-1 -1} def
/vert {0 1} def
/O {0 0} def
/P {O u1 5.5 mulv subv} def
/Q {P horiz1 8 mulv addv} def
/R {Q horiz2 3 mulv subv} def
/S {P horiz2 3 mulv subv} def
/A2 {P R milieu} def
/A1 {A2 vert 4 mulv addv} def
/B1 {A1 u1 2 mulv addv} def
/B2 {A2 S milieu} def
/OO {R horiz1 2 mulv subv vert addv} def

OO u1 vect
OO u2 vect
OO vert 2 mulv vect
<tex>
$$ \vec{u}_1 $$
</tex>
OO OO u1 addv milieu  [1.5 1.5] drtexlabel 
<tex>
$$ \vec{u}_2 $$
</tex>
OO OO u2 addv milieu  [1.5 1.5] dltexlabel 
<tex>
$$ \vec{u}_1\wedge \vec{u}_2 $$
</tex>
OO OO vert 2 mulv addv milieu  [1.5 1.5] crtexlabel 


[P Q R S] polygone


bleu
2 setlinewidth
Q u2 0.1 mulv addv  S u2 0.1 mulv subv (-) line 
P vert 4 mulv addv R vert 4 mulv addv (-) line
[B1 B2] points
16 setfontsize
setTimesItalic
   (B1) B1 ultext
   (B2) B2 urtext
   (D2) Q vert 0.2 mulv addv ultext
   (D1) R vert 4 mulv addv drtext

1 setlinewidth
pointilles
P u1 0.1 mulv addv  R u1 0.1 mulv subv (-) line 

2 setlinewidth
rouge
[A1 A2] points
A1 A2 (-) line
16 setfontsize
setTimesItalic
   (A1) A1 uctext
   (A2) A2 dctext