Tell me the area

Time Limit : 3000/1000ms (Java/Other)   Memory Limit : 65536/32768K (Java/Other)

Total Submission(s) : 4   Accepted Submission(s) : 0

Problem Description    There are two circles in the plane (shown in the below picture), there is a common area between the two circles. The problem is easy that you just tell me the common area.


InputThere are many cases. In each case, there are two lines. Each line has three numbers: the coordinates (X and Y) of the centre of a circle, and the radius of the circle.
OutputFor each case, you just print the common area which is rounded to three digits after the decimal point. For more details, just look at the sample.
Sample Input0 0 2 2 2 1
Sample Output0.108

#include<stdio.h>
#include<math.h>
#define PI acos(-1.0)
int main()
{
    double a1,b1,r1,a2,b2,r2,d;
    double A1,A2,s1,s2,s;
    while(scanf("%lf%lf%lf%lf%lf%lf",&a1,&b1,&r1,&a2,&b2,&r2)!=EOF)
    {
        d=sqrt((a2-a1)*(a2-a1)+(b2-b1)*(b2-b1));
        if(d>=r1+r2)    printf("0.000\n");
        else if(d<=fabs(r1-r2)&&d>=0)
        {
            if(r1>r2)
                    printf("%0.3lf\n",PI*r2*r2);
            else printf("%0.3lf\n",PI*r1*r1);
        }
        else {
            A1=2*acos((d*d+r1*r1-r2*r2)/(2*d*r1));
            A2=2*acos((d*d+r2*r2-r1*r1)/(2*d*r2));
            //cos(A1)=(d*d+r1*r1-r2*r2)/(2*d*r1);
            //cos(A2)=(d*d+r1*r1-r2*r2)/(2*d*r1);
            s1=0.5*r1*r1*sin(A1)+0.5*r2*r2*sin(A2);
            s2=(A1)/2*r1*r1+(A2)/2*r2*r2;
            s=s2-s1;
            printf("%.03lf\n",s);
        }
    }
}