D = (0, 0)
A = (5, 0)
B = (5, 5)
C = (0, 5)
poly1, a, b, c, d = Polygon(D, A, B, C)
M = Point(b)
N = Rotate(M, 270°, A)
poly2, n, a_1, m = Polygon(A, M, N)
e = Line(B, N)
f = Line(D, M)
N' = Intersect(e, f)
poly3, n_1, d_1, b_1 = Polygon(D, B, N)
α = Angle(B, A, D)
g = Line(N, M)
h = Line(A, C)
E = Intersect(h, n_1)
β = Angle(D, E, A)