a = 2.5 (slider from 0 to 10, step 0.1)
c = 2 (slider from 0 to a, step 0.1)
V_1: (a, 0)
V_2: (-a, 0)
F_1: (c, 0)
F_2: (-c, 0)
t = -0.73 (slider from -c to c, step 0.01)
Q: (t, 0)
P: (a * t / c, 1 / c * sqrt((a^(2) - c^(2)) * (c^(2) - t^(2))))
d: (x - c)^(2) + y^(2) = (a - t)^(2)
e: (x + c)^(2) + y^(2) = (t + a)^(2)
D: (a * t / c, (-1) / c * sqrt((a^(2) - c^(2)) * (c^(2) - t^(2))))
f: x^(2) / a^(2) + y^(2) / (a^(2) - c^(2)) = 1