I need to prove that if a,b,c are not in the same plane.

See attachment.

If we put point B in plane then we get line d that is parallel to line b. Also if we put point C then e is parallel to c.

Now we must prove that .

If e is not parallel to a then a and e must intersect but then we would have two lines that are parallel to d which is contradictory so its must be .

Is that proof ok?