d0: y = 0
a = 2 (slider from -5 to 5)
k = 6 (slider from 0 to 20)
F: (0, a)
lieuP: sqrt(x^(2) + (y - a)^(2)) + abs(y) = k
P = Point(lieuP)
perpendP = OrthogonalLine(P, d0)
H = Intersect(perpendP, d0)
h = Segment(P, H)
pf = Segment(P, F)
sP: k - h - pf
b: k
d1: y = b
courbe1 = Parabola(F, d1)
d2: y = (-b)
courbe2 = Parabola(F, d2)
A = Intersect(perpendP, d1)
B = Intersect(perpendP, d2)
lieuQ: sqrt(x^(2) + (y - a)^(2)) = abs(y) + k
eq2: sqrt(x^(2) + (y - a)^(2)) + k = abs(y)
Q = Point(lieuQ)
perpendQ = OrthogonalLine(Q, d0)
L = Intersect(d0, perpendQ)
qf = Segment(Q, F)
l = Segment(Q, L)
sQ: qf - l - k
C = Intersect(d1, perpendQ)
D = Intersect(d2, perpendQ)
pa = Segment(P, A)
pb = Segment(P, B)
qc = Segment(Q, C)
qd = Segment(Q, D)
α = 0.01 (slider from -0.5 to 0.5, step 0.01)
x0: sqrt(k^(2) - a^(2))
f: y = (α * (x^(2) - x0^(2)))