Imagine you are at a point A and you want to go to a point B. You must travel in the direction that takes you from point A to point B. You can plot the positions of A and B, and find the bearing from A to B by superimposing on A a compass, with angles labelled from 0 to 360 degrees.
We can then just read off the bearing from A to B.
If A and B are given as position vectors
andthen it is useful to find the vectorand plot it, on a compass with the centre of the compass acting as A.
The bearing will be given by
ifandare both positive
ifis negative and is positive
ifandare both negative
ifis positive andis negative