#include <bits/stdc++.h>
using namespace std;
#define _rep(i_,a_,b_) for(int i_ = (a_); i_ <= (b_); ++i_)
#define mid ((L+R) / 2)
#define multiCase() int testCnt = in(); _rep(curCase,1,testCnt)
#ifdef ONLINE_JUDGE
#define debug(...) 0
#else
#define debug(...) fprintf(stderr, __VA_ARGS__), fflush(stderr)
#endif
using ll = long long;
using pii = pair<int,int>;

int in(void) { int x; scanf("%d", &x); return x; } ll inl(void) { ll x; scanf("%lld", &x); return x; }
void out(int x) { printf("%d ", x); } void outln(int x) { printf("%d\n", x); }
void out(ll x) { printf("%lld ", x); } void outln(ll x) { printf("%lld\n", x); }
template<typename T> void chkmax(T &a, const T &b) { a = max(a, b); } 
template<typename T> void chkmin(T &a, const T &b) { a = min(a, b); } 
const int kN = 205000;
const double eps = 1e-8, pi = acos(-1);
int n, k;
double A[kN];
int tag[kN << 1];
int main() {
	multiCase() {
		n = in(), k = in();
		_rep(i,1,n) {
			int x = in(), y = in();
			A[i] = atan2(y, x);
			debug("%.5lf\n", A[i]);
		}
		double L = 0, R = pi, ans = 0;
		_rep(i,1,60) {
			debug("mid = %.5lf\n", mid);
			vector<double> d = {-pi, pi};
			_rep(i,1,n) {
				if(A[i] - mid >= -pi) d.emplace_back(A[i] - mid);
				else d.emplace_back(pi - (-pi - (A[i] - mid)));
				if(A[i] + mid <= pi) d.emplace_back(A[i] + mid);
				else d.emplace_back(-pi + (A[i] + mid - pi));
			}
			sort(d.begin(), d.end()), d.erase(unique(d.begin(), d.end()), d.end());
			auto locate = [&](double x) { return lower_bound(d.begin(), d.end(), x) - d.begin(); };
			int mn = n, cur = 0;
			_rep(i,1,n) {
				if(A[i] - mid >= -pi) tag[locate(A[i] - mid)]++;
				else tag[0]++, tag[locate(pi - (-pi - (A[i] - mid)))]++;
				if(A[i] + mid <= pi) tag[locate(A[i] + mid)]--;
				else tag[0]++, tag[locate(-pi + (A[i] + mid - pi))]--;
			}
			int m = d.size();
			_rep(i,0,m - 2) {
				cur += tag[i]; chkmin(mn, cur);
			}
			_rep(i,0,m) tag[i] = 0;
			if(mn >= k) R = mid; else L = mid;
		}
		printf("%.10lf\n", L * 2);
	}
	return 0;
}