%% auteur : gh
100 setxunit
-1 3 setxrange
-1 2 setyrange

/cosa {pi 6 div Cos} def
/sina {pi 6 div Sin} def
/O {0 0} def
/A {cosa sina} def
/B {0 sina sub cosa} def
/M {2 cosa mul 2 sina mul} def
/Mx {2 cosa mul 0} def
/My {0 2 sina mul} def

tracerepere
16 setfontsize
setTimesItalic
   (O) O dltext

<tex> 
$$
\vec{u }
$$ 
</tex> 
0.5 0  [1.5 1.5] dctexlabel 

<tex> 
$$
\vec{v }
$$ 
</tex> 
0 0.5  [1.5 1.5] cltexlabel 

bleu
pointilles
M Mx (-) line
M My (-) line

1 setlinewidth
continu

[M] points
setTimesItalic
   (M) M ultext
   (x) Mx dctext
   (y) My cltext
   (|z|) A {30} uctext
setSymbol
   (q) .5 .12 cctext
   
O M (-) line
/arrowangle -5 store
1 0 O A 0.4 (->) tripointarc