I know the radius "r" of a circle. I have a point "P", always in the circle and always "looking" at the center of the circle, with a certain angle, or overture "a". I know the distance between "P" and the center of the circle. I would like to know the angle or overture "b" from the center, so that "b" covers the same arc of the circle as "a".
Here's a schema explaining the problem :
The goal is to retrieve the angle "b" from all the other parameters. Thanks a lot in advance !