code: function getAreaInternal(coordinates, radius) {
    let area = 0;
    const len = coordinates.length;
    let x1 = coordinates[len - 1][0];
    let y1 = coordinates[len - 1][1];
    for (let i = 0; i < len; i++) {
      const x2 = coordinates[i][0];
      const y2 = coordinates[i][1];
      area += toRadians(x2 - x1) *
          (2 + Math.sin(toRadians(y1)) +
          Math.sin(toRadians(y2)));
      x1 = x2;
      y1 = y2;
    }
    return area * radius * radius / 2.0;
  }
docs: Returns the spherical area for a list of coordinates.
  
  [Reference](https://trs-new.jpl.nasa.gov/handle/2014/40409)
  Robert. G. Chamberlain and William H. Duquette, "Some Algorithms for
  Polygons on a Sphere", JPL Publication 07-03, Jet Propulsion
  Laboratory, Pasadena, CA, June 2007
  
  @param {Array<import("./coordinate.js").Coordinate>} coordinates List of coordinates of a linear
  ring. If the ring is oriented clockwise, the area will be positive,
  otherwise it will be negative.
  @param {number} radius The sphere radius.
  @return {number} Area (in square meters).