A = (-1.54, 4.86)
B = (2.34, 4.86)
C = (4.26, 2.08)
D = (-3.52, 2.08)
Vieleck1, a, b, c, d = Polygon(A, B, C, D)
α = Angle(D, A, B)
β = Angle(A, B, C)
γ = Angle(B, C, D)
δ = Angle(C, D, A)