Source
%% PhS
%% fig_conique_15

45 setxunit
0 12  setxrange
-1.5 7 setyrange

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% procédures
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

/bddroite {
8 dict begin
/kd exch def
/kg exch def
/By exch def
/Bx exch def
/B {Bx By} def
/Ay exch def
/Ax exch def
/A {Ax Ay} def
gsave
[A A B vecteur kg mulv addv A A B vecteur kd mulv addv] ligne
grestore
end
} def

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% definition d'une couleur
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

/coul1 {120 255 div 70 255 div 9 255 div setrgbcolor} def

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% definition des points
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
/H1 {0 0} def
/H2 {11.7 0} def
/V1 {2 -1.8} def
/V2 {2 6.2} def
/K {2 0} def
/Fx {4} def
/F {Fx 0} def
/Sx {3} def
/S {Sx 0} def
/S+ {Sx 7} def
/S- {Sx -2} def
/D {1.8 6} def
/p {2} def
/e {1} def
/A {p 2 mul Sx add dup Sx sub} def
/Axx {p 2 mul Sx add 0} def
/Ayy {Sx p 2 mul} def
/B {p 2 div Sx add p} def
/Byy {Sx p} def

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% parametrage de la parabole
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

/rhox {settvar t cos e mul neg 1 add 1 exch div p mul t cos mul} def
/rhoy {settvar t cos e mul neg 1 add 1 exch div p mul t sin mul} def

/Mx {70 rhox Fx add} def
/My {70 rhoy} def
/M {Mx My} def

/H {M V1 V2 orthoproj} def
/HFv {H F vecteur} def
/HFg {HFv -0.2 mulv H addv} def
/HFd {HFv 0.2 mulv F addv} def

/I {H F milieu} def
/T {V1 V2 M I interdroite} def

/TMv {T M vecteur} def
/TMg {TMv -0.5 mulv T addv} def
/TMd {TMv 1.6 mulv M addv} def

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% tracés
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
continu
1 setlinewidth
[K F M F S A Axx Ayy H I T B Byy] points
[H1 H2] ( ->) ligne
[V1 V2] ligne
[S- S+] ( ->) ligne
[M F] ligne
[M H] ligne
[HFg HFd] ligne
[T F] ligne

M H T angledroit
M F T angledroit
F I M angledroit

coul1
2 setlinewidth
40 320 settrange

1 setlinewidth

rouge
continu
[S Sx 0.8 add 0] ( ->) ligne
[S Sx 0.8] ( ->) ligne

orange
[TMg TMd] ligne

0.6 setlinewidth
vert
pointilles
[Axx A Ayy] ligne
[F B Byy] ligne

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% texte
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

setTimesItalic
noir
(K) K [1.5 dup] dltext
(F) F [1.5 dup] dltext
(M) M -0.1 0.1 addv [1.5 dup] uctext
(H) H -0.1 0 addv [1.5 dup] cltext
(S) S [1.5 dup] dltext
(T) T -0.1 0 addv [1.5 dup] cltext
(I) I -0.1 0 addv [1.5 dup] cltext
vert
(-p/2) K (0 -15) [1.5 dup] dltext
(p/2) F (0 -15) [1.5 dup] dltext
(A) A [1.5 dup] drtext
(2p) Axx [1.5 dup] dctext
(2p) Ayy [1.5 dup] cltext
(p) Byy [1.5 dup] cltext

noir
<latex>
$\mathcal{D}$
</latex>
D [1.5 dup] cltexlabel

<latex>
$\Delta$
</latex>
(x) 11 0 [1.7 dup] dctexlabel