#include <bits/stdc++.h>
using namespace std;
using ld = long long;
using pii = pair<int, int> ;
using ll = long long;
#define mp(a, b) make_pair(a, b)
#define pb(a) push_back(a)
#define F first
#define S second
template<typename T>
pair<T, T> operator-(pair<T, T> a, pair<T, T> b){
    return mp(a.F - b.F, a.S - b.S);
}

template<typename T>
T cross(pair<T, T> a, pair<T, T> b){
    return a.F * b.S - a.S * b.F;
}

template<typename T>
vector<pair<T, T>> getConvexHull(vector<pair<T, T>>& pnts){

    sort(pnts.begin(), pnts.end());

    vector<pair<T, T>> hull;

    for(int i = 0; i < 2; i++){
        int t = hull.size();
        for(pair<T, T> pnt : pnts){
            while(hull.size() - t >= 2 && cross(hull.back() - hull[hull.size() - 2], pnt - hull[hull.size() - 2]) <= 0)
                hull.pop_back();
            hull.pb(pnt);
        }
        hull.pop_back();
        reverse(pnts.begin(), pnts.end());
    }

    return hull;
}

ld dis(pii x, pii s, pii e){
    pii v1 = pii(x.F - s.F, x.S - s.S);
    pii v2 = pii(e.F - s.F, e.S - s.S);

    ld c1 = abs(v1.F * v2.S - v1.S * v2.F);

//    ld c2 = v2.F * v2.F + v2.S * v2.S;

    return c1 ;
}

void solve(){
    int n;
    cin >> n;
    vector<pii> pnts(n);
    
    map<pii, int> cnt;
    for(auto &it : pnts){
        cin >> it.F >> it.S;
        cnt[it] += 1;
    }
    vector<pii> hull = getConvexHull(pnts);
    n = hull.size();
    ld ans = 0;
    if(n == 3){
        ans = dis(hull[0], hull[1], hull[2]);
        ld mi = 1e9;
        for(auto it : pnts){
            if((it == hull[0] && cnt[it] == 1) || (it == hull[1] && cnt[it] == 1) || (it == hull[2] && cnt[it] == 1))
                continue;
            for(int i = 0;i < 3;i ++){
                for(int j = i+1;j < 3;j ++){
                    mi = min(mi, dis(it, hull[i], hull[j]));
                }
            }

        }
        ans -= mi;
        if(ans % 2){
            cout << ans/2 << ".5\n";
        } else {
            cout << ans/2 << "\n";
        }
        return ;
    }
    for(int i = 0;i < n;i ++){
        int l1 = i+1;
        int l2 = i+3;
        for(int j = i + 2;j < n;j ++){
            while(l1 < j && dis(hull[l1], hull[i], hull[j]) < dis(hull[l1+1], hull[i], hull[j]))
                l1 += 1;
            while(l2 != i-1 && dis(hull[l2], hull[i], hull[j]) < dis(hull[l2+1], hull[i], hull[j]))
                l2 += 1;
            ans = max(dis(hull[l1], hull[i], hull[j]) + dis(hull[l2], hull[i], hull[j]), ans);
        }
    }
    if(ans % 2){
        cout << ans/2 << ".5" << "\n";
    } else {
        cout << ans/2 << "\n";
    }
}

int main(){
    cin.tie(0)->sync_with_stdio(0);
    int t = 1;
	cin >> t;
	while(t --){
		solve();
	}
}