we have now
hence angle between OB and OC is
Now, we have,
I think AB here represents the distance between A and B.
there is only one unknown, hence it can be solved.
Thank you for your help!
But unfortunately your solution is outside the level of my current course (I started complex numbers and my further course last week), I do not recognise what you are doing with e. Do you know any solutions with more basic math?