橢圓的定義
Author: 藍邦偉  老師

橢圓的定義

顯示橢圓

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$ \overline{PF}+\overline{PF'}=2a $

移動F與F'決定焦點

滑竿a為長軸長度之半

觀察P點軌跡

θ = 0 rad (slider from 0 to 6.283185307179586, step 0.005235987755982988)
a = 13 (slider from 1 to 25, step 1)
F' = (-20, 0)
C = Circle(F', 2 * a)
A = Intersect(C, xAxis, 2)
Q = Rotate(A, θ, F')
F = (0, 0)
b = Segment(Q, F)
d = LineBisector(b)
e = Segment(Q, F')
P = Intersect(d, e)
c = Segment(P, F')
f = Segment(P, F)
B_1: (x(Corner[1]), 0)
B_2: (x(Corner[2]), 0)
B_3: (0, y(Corner[2]))
B_4: (0, y(Corner[3]))
u = Vector(B_1, B_2)
v = Vector(B_3, B_4)
T_1 = Corner(1)
T_4 = Corner(4)
T_2: (3 * Corner[1] + Corner[2]) / 4
T_3: (3 * Corner[4] + Corner[3]) / 4
多邊形1, t_1, t_2, t_3, t_4 = Polygon(T_1, T_2, T_3, T_4)
g = Segment(T_2, T_3)
h = true
i = (0, 1)
B = Intersect(d, e)
c1: 0.5 * (x(F) - x(F'))
M: 0.5 * F + 0.5 * F'
Γ: (x - x(M))^(2) / a^(2) + y^(2) / (a^(2) - c1^(2)) = 1