tell me about taking bearings, what do you do, let's give you an example, of some bearings to take, erm, and then you can tell me what you're doing, so there's a point there, and we'll call that erm, p, just to be awkward, now let's say what we'll do, this is what we'll d , this is a typical problem in fact, erm, i'll even draw that line on for you to start with, yeah, here's the problem, a ship is sailing due north, okay, and when it's at the point of a it takes a bearing on the lighthouse, so the lighthouse is somewhere, don't know where it is, but bearing of l from a is forty five degrees, and the bearing of l from b, which is when the ship has sailed on a lot further