O = (0.72, 1.12)
c = Circle(O, 5)
B = Point(c)
A = Point(c)
a = Segment(B, O)
b = Segment(O, A)
α = Angle(A, O, B)
d = CircleArc(O, A, B)
C = Point(c)
e = Segment(B, C)
f = Segment(C, A)
β = Angle(A, C, B)