#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;

int main()
{
	//Lets get the math out of the way

	int choice;
	double h; //h = height
	double r; //r = radius
	double w; //w = width
	double a; //a = answer
	double b; //b = base
	const double pi = 3.14159; //pre defined number
	cout << setiosflags (ios::fixed | ios:: showpoint) << setprecision(2);

	// Asking basic questions, using switch #'s 1-4 , if it's above 4 or below 1 it's wrong.  4 ends the program.

	// PG. 237 is information for homework

	// Picking the choice

	cout << "Welcome to the Geometry Calculator\n\n";
	cout << "Please select your choice!\n";
	cout << "1. Area of a Circle\n";
	cout << "2. Area of a Rectangle\n";
	cout << "3. Area of a Triangle\n";
	cout << "4. Quit the program\n\n";
	cout << "Enter your choice here: ";
	cin  >> choice;

	//Validating the choices

	while ((choice < 1) || (choice > 4))
	{
		cout << "The valid choices are 1 through 4.\n";
		cout << "Please select a correct number choice: ";
		cin  >> choice;
	}
//set changes based on choice
switch (choice) {
case 1: cout << "Enter the radius of the Circle: ";
cin  >> r;
a = pi * pow(r,2);
cout << "The area of the Circle is: " << a << endl;
break;

case 2: cout << "Enter the width of the Rectangle: ";
cin  >> w;
cout << "Enter the hight of the Rectangle: ";
cin  >> h;
a = w * h;
cout << "The area of the Rectangle is: " << a << endl;
break;

case 3: cout << "Enter the base of the Triangle: ";
cin  >> b;
cout << "Enter the height of the Triangle: ";
cin  >> h;
a = h * b / 2;
cout << "The area of the Triangle is: " << a << endl;
break;

case 4: break;
}

// system ("PAUSE");

return 0;
}