/*--------------------------------------------------
created by st10 at Fri Oct 14 12:23:21 PDT 2016
--------------------------------------------------*/
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include "circ_area.h"
using namespace std;


/*--------------------------------------------------
 signature: ring_area : double double -> double
 purpose: expects a ring's outer radius and the radius of
   its "hole", and returns the area of that ring

 examples: abs(ring_area(10, 1) - (314.159 - 3.14159)) < .001
           abs(ring_area(2, 1) - (circ_area(2) - 3.14159)) < .001
--------------------------------------------------*/

double ring_area(double outer, double inner)
{
    return circ_area(outer) - circ_area(inner);
}