Help Please

The program pops up but then i get an error saying y2 is being used without being initialized. But i can't find it. If you find any other errors please tell me.

Code:

#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;

double distance(double x1, double y1, double x2, double y2);
double radius(double x1, double y1, double x2, double y2);
double diameter(double rad);
double circumference(double rad);
double area(double rad);
const double Pi = 3.1416;

int main()
{
	double origin1, origin2, pt1, pt2, x1, x2, y1, y2, rad;
	rad = (x1,y1,x2,y2);
	cout << setprecision(2) << fixed << showpoint;
	
	cout << "Please input the origin of your circle" << endl;
	cin >> origin1 >> origin2;
	cout << "Please input a point on the circle" << endl;
	cin >> pt1 >> pt2;
	cout << "Your origin is: " << "(" << origin1 << "," << origin2 << ")" << endl;
	cout << "Your point is: " << "(" << pt1 << "," << pt2 << ")" << endl;
	cout << "The distance between the point and the origin is" 
		 << distance(pt1, origin1, pt2, origin2) << endl;
	cout << "The radius of your circle is: " 
		 << radius(pt1, origin1, pt2, origin2) << endl;
	cout << "The diameter of your circle is: " << diameter(rad) << endl;
	cout << "The circumference of your circle is: "      
		 << circumference(rad) << endl; 
	cout << "The area of your circle is: " << area(rad) << endl;

	return 0;
}

double distance(double x1, double y1, double x2, double y2)
{
	return sqrt(pow(x1-y1,2) + pow(x2-y2,2));
}
double radius(double x1, double y1, double x2, double y2)
{
    return distance(x1, y1, x2, y2);
}
double diameter(double rad)
{
	return 2 * rad;
}
double circumference(double rad)
{
	return Pi * rad; 
}
double area(double rad)
{
	
	return pow(rad, 2); 
}

Code:

	double origin1, origin2, pt1, pt2, x1, x2, y1, y2, rad;
	rad = (x1,y1,x2,y2); // eh??? what's this supposed to be?

what are you trying to do there?

it should be someting like this:

Code:

               cin>>origin1>>origin2;
	cin >> pt1 >> pt2;
                rad=radius(pt1, origin1, pt2, origin2);

The program pops up but then i get an error saying y2 is being used without being initialized.

Code:

double origin1, origin2, pt1, pt2, x1, x2, y1, y2, rad; <====y2 not initialized

rad = (x1,y1,x2,y2);<====y2 being used

If you find any other errors please tell me.

x1, x2, and y1 are being used without being initialized.

Rule #1 in programming: "Always initialize your variables."