///1085422276
#include<bits/stdc++.h>
using namespace std ;
typedef long long ll;
#define mem(a) memset(a,0,sizeof(a))
#define meminf(a) memset(a,127,sizeof(a));

inline ll read()
{
    ll x=0,f=1;char ch=getchar();
    while(ch<‘0‘||ch>‘9‘){
        if(ch==‘-‘)f=-1;ch=getchar();
    }
    while(ch>=‘0‘&&ch<=‘9‘){
        x=x*10+ch-‘0‘;ch=getchar();
    }return x*f;
}
//****************************************

const int inf=9999999;
#define maxn 150
struct node
{
    int x;
    int y;
}p[maxn];
int  d[8];
int n,x[maxn],y[maxn];
int  dis(node a,node b)
{
    return (a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y);
}
bool test()
{
    int ans=inf;
    d[0]=dis(p[0],p[1]);
    d[1]=dis(p[1],p[2]);
    d[2]=dis(p[2],p[3]);
    d[3]=dis(p[3],p[0]);
    d[4]=dis(p[0],p[2]);
    d[5]=dis(p[1],p[3]);
    sort(d,d+6);
    if(d[0]==d[1]&&d[1]==d[2]&&d[2]==d[3]&&2*d[3]==d[4]&&d[4]==d[5])
    {
        return 1;
    }
    return 0;
}
int main(){
    int T=read();
    while(T--){
        scanf("%d",&n);
        for(int i=0;i<n;i++){
            scanf("%d%d",&x[i],&y[i]);
        }
        if(n!=4){
            cout<<"NO"<<endl;
        }
        else {
            for(int i=0;i<4;i++){
                node aa;
                aa.x=x[i],aa.y=y[i];
                p[i]=aa;
            }
            if(test())cout<<"YES"<<endl;
            else cout<<"NO"<<endl;
        }
    }
  return 0;
}