A: (0, 0, 0)
B: (0, 12, 0)
C: (0, 0, 3.5)
D: (0, 12, 3.5)
m1, a, b, d, c = Polygon(A, B, D, C)
räystäs = Segment(C, D)
E: (20, 6, 0)
F: (20, 6, 1.7)
katselija = Segment(E, F)
f = Segment(C, F)
g = Segment(F, D)
α = Angle(D, F, C)