4 \documentclass[12pt]{article}
5 \usepackage[charter]{mathdesign}
19 I=cc intersectionpoint segment(O,A);
20 ce=perpendiculaire(O,A,I);
21 J=cd intersectionpoint ce;
23 C=segment(O,J) intersectionpoint cc;
24 D=segment(O,K) intersectionpoint cc;
26 trace droite(O,O+u*(1,0)) dashed evenly;
27 trace droite(O,O+u*(0,1)) dashed evenly;
30 trace cd dashed withdots;
31 drawoptions(withcolor gris);
34 trace demidroite(A,C);
35 trace demidroite(A,D);
36 trace codeperp(O,C,A,5);
37 trace codeperp(O,D,A,5);
40 arcs0=cercles(O,1.75u) cutafter segment(O,A);
41 arcs1=reverse(cercles(O,2u) cutbefore segment(O,D));
42 arcs2=cercles(O,1.25u) cutafter segment(O,C);
46 label.rt(btex $\phi$ etex,point(0.25*length arcs0) of arcs0);
47 label.rt(btex \ding{172} etex,point(0.5*length arcs1) of arcs1);
48 label.urt(btex \ding{173} etex,point(0.5*length arcs2) of arcs2);
49 label.urt(btex Observateur etex,A);
50 label.llft(btex O etex,O);