#include<stdio.h>
#include<string.h>
#include<math.h>
#define pi 3.14159265358
int main(){
	int i,j,k,m,n;
	double x1,y1,r1,x2,y2,r2,r,r3,s,area;
	double A,B;
	while(scanf("%lf %lf %lf %lf %lf %lf",&x1,&y1,&r1,&x2,&y2,&r2)!=EOF){
	    r=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
		if(r1<r2)
		    r3=r1;
		    r1=r2;
		    r2=r3;
       // printf("r1==%.3lf r2==%.3lf r=%.3lf\n",r1,r2,r);
		if(r>=r1+r2)
		    printf("0.000\n");//相离或相切 
		else if(r<=r1-r2){
		    printf("%.3lf\n",pi*r2*r2);	 
	    }				 
	    else {
		    A=acos((r1*r1+r*r-r2*r2)/(2*r1*r));
			B=acos((r2*r2+r*r-r1*r1)/(2*r*r2));
			s=(r1+r2+r)/2;
            s=sqrt(s*(s-r1)*(s-r2)*(s-r));
	        area=A*r1*r1+B*r2*r2-2*s;
	    
	        printf("%.3lf\n",area);
	    }
    }
	
	return 0;	
}

• Re:WA 了 一下午 是在是不知道哪错了。。。。。。 (865) Icanmey 2008-11-08 13:17:12