Lab Activity #5 - FUNCTIONS Remember to comment your code! Part | The following formula gives the distance between two points (x.y,)and (x.y.). J\": -x) +(y, - ,;,)':. If one of the points corresponds to the center point of a circle, and the other point corresponds to a point on the circle, we can figure out the radius of the circle using the above formula. Here is the main program: #include #include s using namespace std; //the function prototype goes here int main() { double x1,yl,x2,y2; double r; cout>x1>>y1>>x2>>y2; r = radius(x1l,yl,x2,y2); cout