B = (-0.7333117217448869, 0.30684706812178675)
C = (0.7943254977908722, 0.28432661771094014)
a = Segment(B, C)
C_1 = Midpoint(a)
c = Circle(C_1, C)
A = Point(c)
Tên đa giác1, d, a_1, b = Polygon(B, C, A)
α = Angle(B, A, C)