// This program calculates the area of a circle.
// The formula for the area of a circle is Pi times
// the radius squared. Pi is 3.14159.

#include <iostream>
#include <cmath>  //needed for pow function
using namespace std;

int main()
{
	const double PI = 3.14159;
	double area, radius;
	
	cout << "This program calculates the area of a circle.\n";
	cout << "What is the radius of the circle? ";
	cin >> radius;
	area = PI * pow(radius, 2.0);
	cout << "The area is " << area << endl;
	return 0;
}