/*--------------------------------------------------
 Contract: ring_area : double double -> double
 Purpose: Compute and return the area of a ring whose
         outer radius is <outer> and whose "hole" has
         radius <inner>

 Examples: ring_area(5, 3) == 65.9734
--------------------------------------------------*/

// calls circ_area, so must include file containing its header

#include "circ_area.h"
using namespace std;

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