橢圓的第二定義
Author: 藍邦偉  老師
Date: 9 12 月 2012

橢圓的第二定義：

移動d決定準線

$ \overline{PF}=e·d(P,L) $

橢圓的離心率

橢圓的準線

移動e決定離心率

Start

Stop

d = 3.1 (slider from 1 to 5, step 0.1)
e = 0.7 (slider from 0 to 1, step 0.05)
θ = 3.119950570865064 rad (slider from 0 to 6.283185307179586, step 0.01*°)
F = (0, 0)
P: (e * d / (1 - e * cos(θ)); θ)
a = CurveCartesian(e * d / (1 - e * cos(θ)) * cos(θ), e * d / (1 - e * cos(θ)) * sin(θ), θ, 0, 6.283185307179586)
L: x = -d
b = OrthogonalLine(P, L)
B = Intersect(b, L)
c = Segment(P, F)
f = Segment(B, P)
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: 0.7 * Corner[1] + 0.3 * Corner[2]
T_3: 0.7 * Corner[4] + 0.3 * Corner[3]
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)
text2: "e=\frac{c}{a}=" + e
text3: "x=-" + d