Working in the first quadrant only.

I have a circle defined by the standard and known equation of

y = (r^2 - x^2)^-0.5

Where r is the constant radius of the circle.

y' = -x / (r^2 - x^2)^-0.5

0 < y < r

0 < x < r

I have a tangent line to the circle. I know where it intercepts the X axis at a value greater than d. It is the known variable.

I need to find a way to determine the slope of the tangent line or the (x,y) coordinate of where the line intercepts the circle. Actually solving one is solving the other.

intercept = function of distance

distance = radius plus extra