B = (-2.915621397281153, -0.21428909617562852)
C = (0.9338170598941133, -0.2302618698568536)
n = Segment(B, C)
p = OrthogonalLine(C, n)
A = Point(p)
đa giác3, a, b, j_1 = Polygon(B, C, A)
γ = Angle(A, C, B)