#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return true; } return false; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return true; } return false; }
#define vi vector<int>
#define vl vector<ll>
#define vii vector<pair<int,int>>
#define vll vector<pair<ll,ll>>
#define vvi vector<vector<int>>
#define vvl vector<vector<ll>>
#define vvii vector<vector<pair<int,int>>>
#define vvll vector<vector<pair<ll,ll>>>
#define vst vector<string>
#define pii pair<int,int>
#define pll pair<ll,ll>
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define mkunique(x) sort(all(x));(x).erase(unique(all(x)),(x).end())
#define fi first
#define se second
#define mp make_pair
#define si(x) int(x.size())
const int mod=998244353,MAX=300005,INF=15<<26;

const double pi=acos(-1);

int main(){
    
    std::ifstream in("text.txt");
    std::cin.rdbuf(in.rdbuf());
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int Q;cin>>Q;
    while(Q--){
        int N,K;cin>>N>>K;
        vector<double> S;
        for(int i=0;i<N;i++){
            int a,b;cin>>a>>b;
            double z=atan2(b,a);
            S.pb(z-2*pi);
            S.pb(z);
            S.pb(z+2*pi);
        }
        sort(all(S));
        
        double l=0,r=pi;
        
        for(int q=0;q<60;q++){
            double mid=(l+r)/2;
            vector<pair<double,double>> T;
            for(int i=0;i<2*N;i++){
                double a=S[i],b=S[i+K-1];
                if(b-a>mid*2) continue;
                T.pb(mp(b-mid,a+mid));
            }
            bool ok=true;
            double z=-pi;
            for(auto [a,b]:T){
                if(z<=pi&&z<a) ok=false;
                chmax(z,b);
            }
            if(ok) r=mid;
            else l=mid;
        }
        
        cout<<fixed<<setprecision(25)<<r*2<<"\n";
    }
}