View Code of Problem 106

#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<climits>
#include<cmath>
#include<unordered_map>
#include<set>

using namespace std;


int main()
{
	double x1, x2, y1, y2, r;

	while (cin >> x1 >> y1 >> x2 >> y2 >> r) {

		double len = sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));

		if (len == 0) {

			cout << "重合" << endl;
			continue;
		}

		if (len > r * 2) {

			cout << "相离" << endl;
			continue;
		}

		if (len == r * 2) {

			cout << "相切" << endl;
			continue;
		}

		if (len < r * 2) {

			cout << "相交 ";

			double ang1 = acos((r * r + len * len - r * r) / (2 * r * len));
			double ang2 = acos((r * r + len * len - r * r) / (2 * r * len));

			double res = ang1 * r * r + ang2 * r * r - r * len * sin(ang1);
			printf("%.2lf\n", res);
		}
	}
}