A: (-1, 0 - 2)
B: (3, 0, 1)
C: (4, 1, 1)
D: (2, 5, -2)
D_{1}: (x(D), 0, 0)
D_{2}: (0, y(D), 0)
D_{3}: (0, 0, z(D))
d1 = Segment(D, D_{1})
d2 = Segment(D, D_{2})
D3 = NaN
PointIn(Sphere[D, D3])
PointIn(Sphere[D, D3])
PointIn(Sphere[D, D3])
d3 = Segment(D, D_{3})