Hi rasa, you should also consider that there will not be just one new position dependent on the angle difference.
For example, suppose you have the starting position @ (200,200) and you wish to move 2 Degrees. There would therefore be a *circle* of points around which 2 degrees would be possible, thus making your original request much more complicated.
In any event, If you could kindly clarify your intentions perhaps we can find a simpler solution for you.