View Code of Problem 106

#include<bits/stdc++.h>
using namespace std;
#define max 50
int main(){
	double l,R,mm,gg,S,r, x1,x2,y1,y2,nn;
	while(~scanf("%lf %lf %lf %lf %lf",&x1,&y1,&x2,&y2,&r)){
		l = sqrt(pow(x1-x2,2) + pow(y1-y2,2));
		if(l==0)cout<<"重合"<<endl;
		else if(2*r == l)cout<<"相切"<<endl;
		else if(l > 2*r) cout<<"相离"<<endl;
		else if(l < 2*r){
			cout<<"相交"<<" "; 
			mm=acos(l/2.0/r);
			gg=mm*r*r/2.0;
			nn=l*r*sin(mm)/4.0;
			S = 4.0*(gg-nn);
			printf("%.2f\n",S);				
		} 	 
	}
	return 0;
}