code: public static double distance(Coordinate c1, Coordinate c2) {
  		double a = c1.getX() - c2.getX();
  		double b = c1.getY() - c2.getY();
  		return Math.sqrt(a * a + b * b);
  	}
docs: Distance between 2 points.
  
  @param c1 First coordinate
  @param c2 Second coordinate
  @return distance between given points