b = Integral(-x^(2) + 16, -4, 0)
A = Point(xAxis)
d: x(A)
f(x) = -x^(2) + 16
B = Point({d, f(d)})
e = Segment(B, A)
g(x) = -(x - 2)^(2) + 16
C = Point({-(d - 2), 0})
h: x(C)
D = Point({h, g(h)})
i = Segment(C, D)
E = Point({1, y(B)})
foci = 1.5 (slider from 0 to 5, step 0.025)
F = Point({x(E) + foci, y(E)})
j = Segment(E, F)
G = Point({x(E) - foci, y(E)})
k = Segment(E, G)
p = Ellipse(F, G, B)