-a/e

a/e

Với mọi điểm M nằm trên (H), ta luôn có:

 \frac{ MF_1 }{d(M;Δ_1) }  \; = \;  \frac{ MF_2 }{d(M;Δ_2) }  \; = \; e \; (e \; > \; 1) 

O = Intersect(yAxis, xAxis)
a = 10.95 (slider from 0 to 20, step 0.05)
F_1 = Point(xAxis)
F_2 = Mirror(F_1, yAxis)
c: x(F_2)
e: c / a
b: sqrt(c * c - a * a)
d: x * x / (a * a) - y * y / (b * b) = 1.0
Δ_1: x = -(a) / e
Δ_2: x = a / e
A = Intersect(Δ_1, xAxis)
B = Intersect(Δ_2, xAxis)
M = Point(d)
f = Segment(M, F_1)
g = OrthogonalLine(M, yAxis)
C = Intersect(Δ_1, g)
h = Segment(M, C)