B = (0, 8)
h = 4 (slider from 0.5 to 7, step 0.1)
C = (4, 8)
d = Segment(B, C)
a = 60 (slider from 0 to 60, step 0.01)
O: (a, 4)
c = Circle(O, d)
A = Point(c)
e = Circle(O, d)
b = Line(O, A)
D = Intersect(e, b, 2)
P = Rotate(D, (-a) / h, O)
h_1 = Segment(O, P)
r = Segment(O, A)