#include<bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops")
#define ALL(v) v.begin(),v.end()
#define For(i,_) for(int i=0,i##end=_;i<i##end;++i) // [0,_)
#define FOR(i,_,__) for(int i=_,i##end=__;i<i##end;++i) // [_,__)
#define Rep(i,_) for(int i=(_)-1;i>=0;--i) // [0,_)
#define REP(i,_,__) for(int i=(__)-1,i##end=_;i>=i##end;--i) // [_,__)
typedef long long ll;
typedef unsigned long long ull;
#define V vector
#define pb push_back
#define pf push_front
#define qb pop_back
#define qf pop_front
#define eb emplace_back
typedef pair<int,int> pii;
typedef pair<ll,int> pli;
#define fi first
#define se second
const int dir[4][2]={{-1,0},{0,1},{1,0},{0,-1}},inf=0x3f3f3f3f,mod=1e9+7;
const ll infl=0x3f3f3f3f3f3f3f3fll;
const double PI=acos(-1.);
template<class T>inline bool ckmin(T &x,const T &y){return x>y?x=y,1:0;}
template<class T>inline bool ckmax(T &x,const T &y){return x<y?x=y,1:0;}
int init=[](){return cin.tie(nullptr)->sync_with_stdio(false),0;}();
int main(){
    int t_case=1;
    scanf("%d",&t_case);
    while(t_case--){
        int k,n;
        scanf("%d%d",&n,&k);
        V<double>a(n);
        For(i,n){
            int x,y;
            scanf("%d%d",&x,&y);
            a[i]=atan2(y,x);
        }
        sort(ALL(a));
        V<pair<double,int>>b;
        For(i,n){
            int j=i+1;
            while(j<n&&a[i]==a[j])++j;
            b.eb(a[i],j-i);
            i=j-1;
        }
        int m=b.size();
        For(i,m)b.eb(b[i].fi+2*PI,b[i].se);
        double ans=0.;
        int j=0,l=0;
        For(i,m){
            while(l<k)l+=b[j++].se;
            ckmax(ans,b[j].fi-b[i].fi);
            l-=b[i].se;
        }
        printf("%.10lf\n",ans);
    }
    return 0;
}