UVA 11524 - InCircle (计算几何)

这题推推公式就可以了

先利用n1 = m2, n2 = m3,可以构造出所有边的比例关系

然后海伦公式 p = (a + b + c) / 2 S = sqrt(p * (p - a) * (p - b) * (p - c));

又有S = (a + b + c) / r / 2

两式子联立，就可以求出各边长度，然后就可以求出面积

代码：

#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;

int t;
double r, m1, n1, m2, n2, m3, n3;

int main() {
    scanf("%d", &t);
    while (t--) {
        scanf("%lf%lf%lf%lf%lf%lf%lf", &r, &m1, &n1, &m2, &n2, &m3, &n3);
        n2 = n2 / m2 * n1;
        m2 = n1;
        n3 = n3 / m3 * n2;
        m3 = n2;
        double a = m1 + n1, b = m2 + n2, c = m3 + n3;
        double p = (a + b + c) / 2;
        double tmp = sqrt(p * (p - a) * (p - b) * (p - c));
        double x = r / tmp * (a + b + c) / 2;
        printf("%.4f\n", x * x * tmp);
    }
    return 0;
}

UVA 11524 - InCircle (计算几何)

原文：http://blog.csdn.net/accelerator_/article/details/44649635