With this program I need to be able to find the circumference, area, diameter and radius of a circle. Here is what I have, please let me know of any advice you have:

```
#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main ()
{
int x1;
int x2;
int y1;
int y2;
int dx;
int dy;
cout << "Enter the center point of the circle: " << endl;
cin >> (x1, y1) >> (x2, y2);
cout << "Enter a point on the circle" << endl;
cin >> (x1, y1) >> (x2, y2);
cout << endl;
int distance (x1, y1, x2, y2)
{
dx = x2 - x1;
dy = y2 - y1;
float dsquared = dx * dx + dy * dy;
float dresult = sqrt (dsquared);
cout << "The distance of the circle is: " << dresult << " " << endl;
}
int radius (x1, y1, x2, y2)
{
float radius = distance
float dresult = area (radius);
cout << "The radius of the circle is: " << dresult << " " << endl;
}
int circumference (float radius)
{
float circumference = 3.1416 * (radius * 2);
cout << "The circumference of the circle is: " << circumference << " " << endl;
int area (float radius)
{
float area = (radius * radius) * 3.1416;
cout << "The area of a circle is: " << area << " " << endl;
cout << ' ' << endl;
system ("pause");
return 0;
}
```