MAB = [3.5, -0.5, -1.5]
MBC = [0.5, -3.5, 0]
MCD = [-2, -4, 0]
MAD = [1, -1, -1.5]
Gerade durch MAB und MBC
g1: X = [3.5, -0.5, -1.5] + r·([0.5, -3.5, 0] - [3.5, -0.5, -1.5])
g1: X = [3.5, -0.5, -1.5] + r·[-3, -3, 1.5]
Gerade durch MBC und MCD
g2: X = [0.5, -3.5, 0] + r·([-2, -4, 0] - [0.5, -3.5, 0])
g2: X = [0.5, -3.5, 0] + r·[-2.5, -0.5, 0]
usw.