∡ BEC = (sđ BC - sđ CA)/2

O = (35.088428321678315, -0.056351981351984964)
B_1 = (37.55580011655011, -2.038339160839164)
c = Circle(O, B_1)
E = (39.800703962703956, 4.615474941724937)
B = Point(c)
a = Ray(E, B)
A = Intersect(c, a, 2.0)
C_1 = Midpoint(E, O)
d = Circle(C_1, E)
C = Intersect(c, d, 2.0)
b = Ray(E, C)
e = Segment(A, C)
α = Angle(A, E, C)
β = Angle(B, A, C)
γ = Angle(E, C, A)