A = (-2, -3)
B = (10, -3)
C = (6, 5)
Vieleck1, a, b, c = Polygon(B, C, A)
h_a = OrthogonalLine(A, a)
h_b = OrthogonalLine(B, b)
h_c = OrthogonalLine(C, c)
H = Intersect(h_c, h_a)
D = Intersect(h_b, b)
E = Intersect(h_c, c)
F = Intersect(h_a, a)
α = Angle(C, E, A)
β = Angle(H, F, B)
γ = Angle(H, D, C)