I'm developing a mathematical formula for a programming interface. Please see following image for description:
As you will see in the diagram, I have variables that will be set by my software( a, d and x), but I need a function to calculate the radius of the big circle ( r ). I can't think of any solution and I don t really need an exact one, approximation will work (rounded up even better) if there isn't any solution.
Any help will be much appreciated.