B = (4.633278697532868, -6.919359871134684)
C = (15.25155769555886, -6.6639373522818275)
a = Segment(B, C)
b = LineBisector(a)
A = Point(b)
đa giác1, b_1, c, a_1 = Polygon(A, B, C)
d = Line(B, C)
D = Point(d)
E = Mirror(D, b)
đa giác2, a_2, c_1, d_1 = Polygon(A, D, B)
đa giác3, b_2, c_2, d' = Polygon(A, E, C)
α = Angle(C, B, A)
β = Angle(A, C, B)
γ = Angle(B, D, A)
δ = Angle(A, E, C)