感谢支持（谢谢）

解题思路:

#include <bits/stdc++.h>

using namespace std;

int main()

{

    double xa,ya,xb,yb,xc,yc;

    cin>>xa>>ya>>xb>>yb>>xc>>yc;

    double a=sqrt((xa-xb)*(xa-xb)+(ya-yb)*(ya-yb));

    double b=sqrt((xa-xc)*(xa-xc)+(ya-yc)*(ya-yc));

    double c=sqrt((xb-xc)*(xb-xc)+(yb-yc)*(yb-yc));

    double p=(a+b+c)/2;

    double s=sqrt(p*(p-a)*(p-b)*(p-c));

    printf("%.2lf",s);

    return 0;

}

注意事项:

参考代码: