C++ 解法, 执行用时: 3ms, 内存消耗: 404K, 提交时间: 2021-12-15 00:31:07

#include<iostream>
using namespace std;

int t;
double x1,x2,x3,x4,y1,y2,y3,y4;

int main(){
    cin>>t;
    while(t--){
        cin>>x1>>y1>>x2>>y2>>x3>>y3>>x4>>y4;
        double e=x1*x1-x2*x2+y1*y1-y2*y2;
        double f=x1*x1-x3*x3+y1*y1-y3*y3;
        double d=4*(x1-x2)*(y1-y3)-4*(x1-x3)*(y1-y2);
        double x=(e*2*(y1-y3)-f*2*(y1-y2))/d;
        double y=(f*2*(x1-x2)-e*2*(x1-x3))/d;
        double r=(x1-x)*(x1-x)+(y1-y)*(y1-y);
        double res=(x-x4)*(x-x4)+(y-y4)*(y-y4);
        if(abs(r-res)<1e-12) cout<<"yes\n";
        else cout<<"no\n";
    }
}