%% auteur : gh
100 setxunit
-2.5 2.5 setxrange
-1.5 1.5 setyrange

/O {0 0} def
/a 2 def
/b 1 def
/c {a 2 exp b 2 exp sub sqrt} def
/F {c neg 0} def
/F' {c 0} def
/Dx {a 2 exp c div neg 0} def
/Dx' {a 2 exp c div 0} def
/D {Dx Dx 0 1 addv} def
/D' {Dx' Dx' 0 1 addv} def


/X {Cos a mul} def
/Y {Sin b mul} def

traceaxes
axesarrow
16 setfontsize
setTimesItalic
   (O) O dltext

4 setlinewidth
noir
0 pi 2 mul settrange
{X} {Y} courbeparam

2 setlinewidth
continu
[F F'] points
D droite
D' droite
setTimesItalic

noir
setTimesItalic