/*--------------------------------------------------
created by smtuttle at Tue Oct 19 14:15:27 PDT 2010
--------------------------------------------------*/
#include <iostream>
#include <cmath>
#include "circ_area.h"
using namespace std;


/*--------------------------------------------------
 Contract: ring_area : double double -> double
 Purpose: expects the outer radius of a ring and the radius
         of the ring's "hole" -- its outer and inner
	 radii, if you will -- and produces the arrea
         of the ring

 Examples: abs(ring_area(100, 10) - 31101.8) < .1
          ring_area(10, 0) == circ_area(10) - circ_area(0)
--------------------------------------------------*/

double ring_area(double outer_rad, double inner_rad)
{
    return circ_area(outer_rad) - circ_area(inner_rad);
}