%% auteur : gh %% conique_ellipse_pythagore.jps 1000 setwidth 600 setheight -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 $$O$$ O [3 dup] dltexlabel 6 setlinewidth rouge O F' (-) line O 0 b (-) line F' 0 b (-) line F' O 0 b angledroit 2 setlinewidth noir /dy {0 0.1} def /dx {0.1 0} def O dy subv F' dy subv (<->) line $$c$$ O dy subv F' dy subv milieu [3 dup] dctexlabel O dx subv 0 b dx subv (<->) line $$b$$ O dx subv 0 b dx subv milieu [3 dup] cltexlabel 0 b dx dy addv addv F' dx dy addv addv (<->) line $$a$$ 0 b dx dy addv addv F' dx dy addv addv milieu [3 dup] urtexlabel 2 setlinewidth vert 0 pi 2 mul settrange {X} {Y} courbeparam 2 setlinewidth continu bleu [F F'] points D droite D' droite $$F$$ F [3 dup] dctexlabel $$F'$$ F' [3 dup] drtexlabel $$D$$ Dx 0 1.5 subv [3 dup] urtexlabel $$D'$$ Dx' 0 1.5 subv [3 dup] urtexlabel