#include <iostream>
using namespace std;

// area calculation program that employs functions
// Albert Levi 17 July, 2002

void calculate_area (float radius)
{
	float area;
	area = 3.14*radius*radius;
	cout << "The area of a circle with radius " << radius << " is " << area << endl;
}

int main()
{
	float r;
	
	r = 3;
	
	calculate_area(r);
	
    calculate_area(2.5);

	calculate_area(r/2);
	
    return 0;
}