Question

If P=(2,1,-1) & Q=(4,7,7) find the point lying on the line segment PQ lying 2/3 of the way from P to Q.I found magnitude of line segment PQ=sqrt104 & multiplied that by 2/3.my next step is wrong i think so to not mislead u i won't type it but what is it?

Answer 1

The vector pointing from P to Q is Q-P. So you need P+(2/3)(Q-P). I don't think you need the length of the line segment at all.

Answer 2

2d only but works the same way in space.