S_1 = (12.96, -3.76)
T = (19.26, -4.18)
k_1 = Circle(S_1, T)
f = Line(S_1, T)
S_2 = Point(f)
k_2 = Circle(S_2, T)
a = 0 (slider from 0 to 4, step 1)
A = Intersect(k_1, f, 2)
B = Intersect(k_2, f, 2)
g = Line(S_1, S_2)
C = Midpoint(A, B)
c = Hyperbola(S_1, S_2, C)
d = Ellipse(S_1, S_2, C)