View Code of Problem 106

    #include<stdio.h>
    #include<math.h>
    int main()
    {
    	float x1,x2,y1,y2;
    	float r;
    	while(scanf("%f %f %f %f %f",&x1,&y1,&x2,&y2,&r)!=EOF)
    	{
    		float l=sqrt(pow(x2-x1,2)+pow(y2-y1,2));
    		if(l==0)
    		{
    			printf("重合\n");
    		}
    			
    		else if(l>2*r)
    		{
    				printf("相离\n");
    		}
    		else if(l==2*r)
    		{
    				printf("相切\n");
    		}
    		else
    		{
    				double ang1=acos(l/(2*r));
        		 	printf("相交 %.2lf\n",2*ang1*r*r-l*r*sin(ang1));
    		}
    	}
    }