%% auteur : gh
%% conique_parabole.jps
700 setwidth
1200 setheight
-1.5 2 setxrange
-3 3 setyrange

/O {0 0} def
/f {sqrt 2 mul} def
/g {sqrt 2 mul neg} def
/F {1 0} def
/D {-1 0 -1 1} def

traceaxes
axesarrow
<tex>
$$O$$
</tex>
O [3 dup] dltexlabel

3 setlinewidth
continu
bleu
[F] points
D droite
<tex>
$$F$$
</tex>
F [3 dup] dltexlabel
<tex>
$$D$$
</tex>
-1 0 0 3 addv [3 dup] dltexlabel

6 setlinewidth
rouge
0.0001 2 {f} Courbe
0.0001 2 {g} Courbe

2 setlinewidth
noir
/x 0.5 def
/M {x dup f} def
/H {-1 x f} def
[M H] points
<tex>
$$M$$
</tex>
M [3 dup] ultexlabel
<tex>
$$H$$
</tex>
H [3 dup] cltexlabel

F M (-) line
M H (-) line

<latex> 
$$
\frac{p}{2}
$$ 
</latex> 
F  [3 dup] drtexlabel 

<latex> 
$$
-\frac{p}{2}
$$ 
</latex> 
-1 0  [3 dup] dltexlabel