Couple of things:
1. Many of us sort of frown upon the insistent, borderline rude titles of which your post serves as an example. We often ignore such posts, and so, it's in your own interest to give them a simple, courteous title descriptive of the problem at hand. You'll probably get better results that way.
2. We also frown upon threads started in categories with which they have nothing to do, such as yours. It is, so far as I can tell, a basic geometry question, having nothing directly to do with Calculus. So for the same reasons as given above, you might want to pay attention to where you post things in the future.
3. Lastly, you need to be more clear in describing your question. I assume, but only after some considerable effort, that the "A" and "B" in your question are points in the plane, making AB a line. I'm not sure what P | AB is supposed to indicate, nor what the 3:1 ratio has to do with it. Is P a segment of AB having one third AB's length? 3 times it's length?
In summary, you need to give a little to get a little. Many of us would love to help you out if only you would take a moment or two to make things a bit easier on us.