#include <iostream>
#include <math.h>
using namespace std;
#define PI 3.14159265

int main()
{
int again(void);
double pyth(double a, double b);
double rpa(int n, double sidelength);
double a, b, sidelength;
int x, n;
double ans;

cout << "What math solver would you like to use?\n" << "1. Pythagorean theorem\n" << "2. Regular Polygon Area\n";
cin >> x;
switch (x)
{
case 1: cout << "What is a?\n";
	cin >> a;
	cout << "What is b?\n";
	cin >> b;
	ans = pyth(a, b);
	cout << "The hypotenuse is " << ans << " units long.\n\n";
	again();
	break;

case 2: cout << "How many sides are there?\n";
	cin >> n;
	cout << "What is the side length?\n";
	cin >> sidelength;
	ans = rpa(n, sidelength);
	cout << "The area of the polygon is " << ans << ".\n\n";
	again();
	break;
}

return 0;

}

double pyth(double a, double b)
{
	double aa, bb, cc, c;
	aa = a * a;
	bb = b * b;
	cc = aa + bb;
	c = sqrt(cc);
	return c;
}

double rpa(int n, double sidelength)
{
	double iam, hsl, apothem, area;
	iam = ((n - 2) * 180) / n;
	iam /= 2;
	hsl = sidelength / 2;
	apothem = hsl * tan(iam*PI/180);;
	area = 0.5 * ((apothem) * (n * sidelength));
	return area;
}

int again(void)
{
	int main(void);
	char answer;
	cout << "Would you like to solve another problem? (y / n)\n";
	cin >> answer;
	switch (answer)
	{
		case 'y': main(); break;
		case 'n': return 0; break;
		default: again(); break;
	}
}