I have a tricky problem, and it has been years since Geometry.
I need to calculate the points on and inner and outer circle based on a center line and a known Chord Length (L) and two know Radius (A, B)
I am trying to locate A1, A2 and B1, B2
Here is a diagram to help explain.
For the first, a circle of radius "r", centered at the origin has an equation x^2 + y^2 = r^2 The chord is divided equally above and below the x-axis, so the distance to A1 for example would be L/2, where L is the length of the chord. That is the y-value. Sub that into the value for y and you have x^2 = r^2 - (L/2)^2 from which you can find the x-value.
For the second, the only change is the radius length. If the first is r, the second could be R.