ABCD is a tetrahedron. The three edges at B are mutually perpendicular. O is the
midpoint of AB and K is the foot of the perpendicular from O to CD.
Given that AC = x, BD = y, AB = z, and:
2*x*y = z^{2}
Determine the ratio: volume(KOAC)/volume(KOBD) in terms of x, y and z.