static polyCircumradius(s, n) {
    return s / (2 * Math.sin(Math.PI / n));
  }
Returns the circumradius of a n-sided regular polygon with a given side-length.

@static
@param {Number} s The side length of the regular polygon.
@param {Number} n The number of sides.
@returns {Number} The circumradius of the regular polygon.