I want to find two points across diameter a circle, based on a known position and an isosceles triangle produced from three points that I'll describe as a (the known position) and b and c ( the unknown positions across the diameter of the circle ). This may be pretty basic, so excuse my noobocity.
I think my illustration will describe it better.
point1a, 2a, and 3a positions are known. This center point of the circle is known (here in the center of the 400 x 400 square). The diameter of the circle is known. I want to find position b and c for each a.