Thread: moving a circular object along a surface and rotating it around the end

Im trying to move a circular object along a surface and then rotate it around the corner / end point of that surface.
I think it can be soloved using trigonometry, but not 100 percent sure.

I can move the object along the surface using this calculation...offset = tan(A) x radius of circle. this gives me a distance I can offset the circle by, but having trouble with the rotation.
please see attached image for a better understanding of what i am trying to achieve.



It would be really helful if anyone can give me any advice on how to to resolve this problem.
thanks in advance.