code: public boolean isRectangular () {
          return (_isPolygonal) && (_rulesSize <= 5) && (_coordsSize <= 8) &&
              (_coords[1] == _coords[3]) && (_coords[7] == _coords[5]) &&
              (_coords[0] == _coords[6]) && (_coords[2] == _coords[4]);
      }
docs: Returns true if this area is rectangular.