[" If "A(4,8,12),B(2,4,6),C(3,5,4)" and "D(5,8,5)" are four points,show that the lines "],[AB" and "+CD" intersect."]

If A(4,8,12), B(2,4,6), C(3,5,4) and D(5,8,5) are four points, show that the lines vec(AB) and vec(CD) intersect.

If A(1,2,3),B(4,5,7) ,C(-4,3,-6) and D(2,9,2) are four given points then find the angle between the lines AB and CD.

Prove that for the four points A(4,8,12),B(2,4,6),C(3,5,4) and D(6,8,5) the lines AB and CD intersect

If A(1,2,3),B(4,5,7) ,C(-4,3,-6) and D(2,9,2) are four given points then find the angle between the lines AB and CD. a) (pi)/(6) b) (pi)/(4) c) (pi)/(3) d) 0

If A(2, 3, 4), B(5, 4, -1), C(3, 6, 2) and D(1, 2, 0) be four points, show that vec(AB) is perpendicular to vec(CD) .

Let A(-2, 0, 3), B(0, 3, -3), C(3, 3, 5) and D(5, 4, 3) be four given points, find the acute angle between the lines AB and CD.