Phương trình chính tắc của elip:

 \frac{ x² }{a² } \; + \;  \frac{ y² }{b² } \; = \; 1 \; (a>b>0)  

O_1 = Intersect(yAxis, xAxis)
a = 5.5 (slider from 0 to 15, step 0.1)
O = Intersect(yAxis, xAxis)
b = 3.3 (slider from 0 to 14, step 0.1)
c: sqrt(a * a - b * b)
d: x * x / (a * a) + y * y / (b * b) = 1.0
F_2: (c / 2.0, 0.0)
F_1: (-(c) / 2.0, 0.0)
M = Point(d)
e = Segment(F_1, M)
f = Segment(M, F_2)
B_1, B_2 = Intersect(d, yAxis)
A_1, A_2 = Intersect(d, xAxis)
g = OrthogonalLine(B_2, yAxis)
h = OrthogonalLine(B_1, yAxis)
i = OrthogonalLine(A_2, xAxis)
j = OrthogonalLine(A_1, xAxis)
P = Intersect(g, j)
Q = Intersect(g, i)
R = Intersect(h, i)
S = Intersect(h, j)
k = Segment(P, Q)
l = Segment(Q, R)
m = Segment(R, S)
n = Segment(S, P)