A = (3, 5)
B = (7, 5)
poly1, f, g, h, i, C, D = Polygon(A, B, 4)
I = Midpoint(A, B)
K = Midpoint(B, C)
j = Segment(I, C)
k = OrthogonalLine(B, j)
H = Intersect(j, k)
l = Segment(B, H)
L = Midpoint(I, B)
m = Line(H, L)
n = Line(H, K)
α = Angle(B, H, C)