Question

If you have four lines how can you position them so that three are concurrent with each other and two are parallel to each other?

Answer 1

Concurrent lines are lines that intersect at a single point.
Well, a figure cannot be shown here, but try to draw/imagine.

For instance, in an x-y plane, you have the three concurrent lines that intersect at the origin. Now, in order to have one pair of parallel lines, the fourth line must lie in the z-axis, and must be parallel to only one of the three lines. It cannot lie on the x-y plane also because it will intersect the other two lines (which will make them concurrent with each other - which we cannot assume).

hope it's clear ^^;