1 #include <cstdio> 2 #include <cstring> 3 #include <cmath> 4 #include <algorithm> 5 using namespace std; 6  7 int t; 8 double r,R; 9 struct point10 {11     double x,y;12     double r;13 };14 15 double circle_area(point a,point b)16 {17     double s,d,t,t1;18     d=sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));19     if(d>=a.r+b.r) s=0;20     else if(d<=fabs(a.r-b.r)) s=min(acos(-1.0)*a.r*a.r,acos(-1.0)*b.r*b.r);21     else22     {23         t=(a.r*a.r+d*d-b.r*b.r)/2.0/d;24         t1=sqrt(a.r*a.r-t*t);25         s=-d*t1+a.r*a.r*acos(t/a.r)+b.r*b.r*acos((d-t)/b.r);26     }27     return s;28 }29 30 int main()31 {32     scanf("%d",&t);33     for(int cas=1; cas<=t; cas++)34     {35         scanf("%lf%lf",&r,&R);36         point st1,st2,st3,st4;37         double x,y;38         scanf("%lf%lf",&x,&y);39         st1.x=st2.x=x;40         st1.y=st2.y=y;41         st1.r=r;42         st2.r=R;43         scanf("%lf%lf",&x,&y);44         st3.x=st4.x=x;45         st3.y=st4.y=y;46         st3.r=r;47         st4.r=R;48         double ans=0;49         ans+=circle_area(st2,st4);50         ans-=circle_area(st1,st4);51         ans-=circle_area(st2,st3);52         ans+=circle_area(st1,st3);53         printf("Case #%d: %.6lf\n",cas,ans);54     }55     return 0;56 }