B = (-0.8158867065846573, -0.0684937720589894)
C = (0.5390937264679445, -0.06474036365718165)
Tên đa giác1, a, a_1, b, A = Polygon(B, C, 3.0)
D = Midpoint(a)
c = Segment(A, D)
E = Midpoint(a_1)
d = Segment(E, B)
G = Intersect(c, d)
α = Angle(C, D, G)