O = (5, -2)
B_1 = (9, -2)
r = Segment(O, B_1)
c = Circle(O, 4)
A = Point(c)
d = Circle(A, O)
e = Circle(A, O)
B = Intersect(c, e, 2)
a = Segment(A, B)
C = Point(c)
poly1, b, c_1, a_1 = Polygon(C, A, B)
α = Angle(B, C, A)