Tečna paraboly
Author: Radka Hamříková

A = (0, 2.42)
B = (0, -3.3)
d = Line(A, B)
F = (3.74, -1.12)
c = Parabola(F, d)
o = OrthogonalLine(F, d)
V = Intersect(c, o)
a = 1.8 (slider from -10 to 10, step 0.1)
a_1: y = a
T, C = Intersect(c, a_1)
b = Line(F, T)
D = Intersect(a_1, d)
t = Tangent(T, c)
e = CircleArc(T, D, F)
f = Line(F, D)
W = Intersect(f, t)
v = Tangent(V, c)