T403

s_{1} = Vector((-4, 4, 4))
s_{2} = Vector((-1, -2, 1))
A: (4, -4, 0)
C: (3, 3, 1)
f = Line(A, s_{1})
g = Line(C, s_{2})
B = Intersect(g, f)
D = Intersect(g, xOyPlane)