A = (-9, 8)
B = (-2, 8)
C = (-5, 12)
veelhoek1, c, a, b = Polygon(A, B, C)
d = OrthogonalLine(A, c)
e = OrthogonalLine(B, c)
f = OrthogonalLine(C, e)
D_1 = Intersect(d, f)
E = Intersect(e, f)
g = OrthogonalLine(C, c)
D = Intersect(c, g)
h = Segment(D, C)
veelhoek2, a_1, b_1, e_1, d_1 = Polygon(A, B, E, D_1)
α = Angle(B, D, C)