#include <iostream>
#include <cmath>

using namespace std;

const double cot = 1/tan(M_PI/7) ;

double HeptagonArea(double EdgeLength)
{
    return 7*pow(EdgeLength, 2)*cot/4 ;
}

double CircleArea(double radius)
{
    return M_PI*pow(radius, 2) ;
}
bool ApproxEqual(double first, double second, double eps=1e-5)
{
    return abs(first-second) < eps ;
}
int main()
{
    double elength ;
    double r ;
    cout << "Please enter the edge length of heptagon: " ;
    cin >> elength ;
    cout << "Please enter the radius of circle: " ;
    cin >> r ;
    cout << "The area of given heptagon is: " << HeptagonArea(elength) << " and the are of given circle is: " << CircleArea(r) << endl;

    if (!ApproxEqual(HeptagonArea(1), 3.63391))
        cout << "Oops! Heptagon area(1) != 3.63391\n" ;
    if (!ApproxEqual(HeptagonArea(5), 90.8478, 1e-4))
        cout << "Error! Heptagon area(5) != 90.8478\n" ;
    if (!ApproxEqual(HeptagonArea(10), 363.391, 1e-3))
        cout << "Wrong! Heptagon area(10) != 363.391\n" ;

    if (!ApproxEqual(CircleArea(1), 3.14159))
        cout << "Oh no! Circle area(1) != 363.391\n" ;
    if (!ApproxEqual(CircleArea(5), 78.5398, 1e-4))
        cout << "Stop! Circle area(5) != 363.391\n" ;
    if (!ApproxEqual(CircleArea(10), 314.159, 1e-3))
        cout << "It would seem something is not quite right! Circle area(10) != 314.159\n" ;
    return 0;
}