View Code of Problem 106

#include<stdio.h>
#include<math.h>

int main()
{
	double x1, y1, x2, y2, r;
	double d;
	while(scanf("%lf%lf%lf%lf%lf", &x1, &y1, &x2, &y2, &r) != EOF)
	{
		if(x1 == x2 && y1 == y2)
		{
			printf("重合\n");
			continue;
		}
		d = sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1));
		if(d == 2*r)
			printf("相切\n");
		else if(d > 2*r)
			printf("相离\n");
		else
		{
			double s;
			printf("相交 ");
			double th = acos(0.5*d/r);
			s = th * r * r;
			s -= sqrt(r*r-d*d/4) * d/2;
			s *= 2;
			printf("%.2lf\n", s);
		}
	}
	return 0;
}