code: public double getNativeRingRadius(IRing ring, double bondLength) {
          int size = ring.getAtomCount();
          double radius = bondLength / (2 * Math.sin((Math.PI) / size));
          return radius;
      }
docs: Returns the ring radius of a perfect polygons of size ring.getAtomCount()
  The ring radius is the distance of each atom to the ringcenter.
  
  @param   ring  The ring for which the radius is to calculated
  @param   bondLength  The bond length for each bond in the ring
  @return  The radius of the ring.