Are you willing to do some calculations yourself?
I assume you are saying the curve, which looks like an ellipse, is supposed to be an arc of a circle.
If so, the figure is called a segment of a circle, and you can find at least part of the work by searching for "circular segment formulas" or "circular segment calculator". That can tell you the radius of the circle; then you can use the equation of a circle to find y for any position x.