#include <iostream>
#include <cmath>
 
 
using namespace std;
 
 
int main ()
 
{
		double const pi=3.14159;
		int radius,
			length,
			width,
			base,
			height,
			choice;
			double	area;
 
 
 
	//Display the menu and get the user's choice
		cout << "         Geometry Calculator \n\n";
		cout << "1. Calculate the Area of a Circle\n";
		cout << "2. Calculate the Area of a Rectangle\n";
		cout << "3. Calculate the Area of a Trainge\n";
		cout << "4. Quit\n";
		cout << "\n";
 
		cout <<"Enter your choice (1-4): ";
		cin >> choice;
		cout << "\n";
 
 
		   if (choice==1)
		   {cout << "Please enter the radius of the circle: ";
		    cin >> radius;
			while (radius<0)
			{cout << "Please enter a positive number: ";
			cin >> radius;}
			area = radius * pi;
			cout << "The area of the circle is: " << area << endl;}
 
		   else if (choice==2)
		   {cout << "Please enter the length of the rectangle: ";
			cin >> length;
			while (length<0)
			{cout << "Please enter a positive number: ";
			cin >> length;}
			cout << "Please enter the width of the rectangle: ";
			cin >> width;
			while (width<0)
			{cout << "Please enter a positive number: ";
			cin >> width;}
			area = length * width;
			cout << "The area of the rectangle is: " << area << endl;}
 
			else if (choice==3)
			{cout << "Please enter the base length of the triangle: ";
			cin >> base;
			while (base<0)
			{cout << "Please enter a positive number: ";
			cin >> base;}
			cout << "Please enter the height of the triangle: ";
			cin >> height;
			while (height<0)
			{cout << "Please enter a positive number: ";
			cin >> height;}
			area = (base * height)/2;
			cout << "The area of the triangle is: " << area << endl;}
 
			else if (choice==4)
			{cout << "Thanks for trying the Geometry Calculator\n";}
 
			else
			{cout << "You can only select options 1-4, run the program again and select a option 1-4\n"; }
 
 
		return 0;
 
}