The 2018 JUST Collegiate Programming Contest I题 Circle

小学数学题

#include<cstdio>
#include<cmath>
using namespace std;
const double PI = 3.1415926;
int main () {
	int t, a, b;
	double d, dayuan, xiaoyuan, sanjiao, r, xiaoyuanR, ans;
	scanf("%d", &t);
	while (t--) {
		scanf("%d %d %lf", &a, &b, &d);
		r = d / 2;
		dayuan = PI * r * r;
		xiaoyuanR = sqrt(2*r*r) / 2;
		xiaoyuan = PI * xiaoyuanR * xiaoyuanR;
		sanjiao = (r * r) / 2;
		ans = xiaoyuan / 2 + sanjiao - dayuan/4;
		printf("%.8lf\n", ans*4);
	}
	return 0;
}