A = (0, 0)
B = (6, 0)
O = Midpoint(A, B)
c = Circle(O, B)
H = (2.5, 0)
a = Segment(A, B)
b = OrthogonalLine(H, a)
E, C = Intersect(c, b)
d = Segment(C, H)
α = Angle(B, H, C)
e = Segment(A, C)
f = Segment(B, C)
g = Segment(C, O)
H' = Midpoint(f)
h = Segment(O, H')
β = Angle(O, H', B)