A = (1, 4)
B = (4, 4)
poly1, f, g, h, i, C, D = Polygon(A, B, 4)
j = Segment(C, A)
M = Point(j)
k = OrthogonalLine(M, h)
l = OrthogonalLine(M, i)
P = Intersect(l, i)
Q = Intersect(k, h)
m = Line(B, Q)
n = Line(P, C)
α = Angle(n, m)