View Code of Problem 106

    #include<stdio.h>
    #include<math.h>
    int main()
    {
    	double x1,x2,y1,y2;
    	double r;
    	while(scanf("%lf %lf %lf %lf %lf",&x1,&y1,&x2,&y2,&r)!=EOF)
    	{
    		if(x1>20||x2>20||y1>20||y2>20||r>20||x1<-20||x2<-20||y1<-20||y2<-20||r<-20)
    		break;
    		if(x1==x2&&y1==y2)
    		{
    			printf("重合\n");
    		}
    		else
    		{
    			double x=x1-x2;
    			double y=y1-y2;
    			double l=sqrt(x*x+y*y);
    			if(l>2*r)
    			{
    				printf("相离\n");
    			}
    			else if(l==2*r)
    			{
    				printf("相切\n");
    			}
    			else
    			{
    				double ang1=acos((r*r+l*l-r*r)/2*(l*r));
    				double ang2=acos((r*r+l*l-r*r)/2*(l*r));
    				double area=ang1*r*r*2-sin(ang1)*r*l;
    				printf("相交 %.2lf\n",area);
    			}
    		}
    	}
    }