1 /*************************************************************************
  2     > File Name: code/hdu/3264.cpp
  3     > Author: 111qqz
  4     > Email: rkz2013@126.com 
  5     > Created Time: 2015年11月06日 星期五 14时57分47秒
  6  ************************************************************************/
  7 
  8 #include<iostream>
  9 #include<iomanip>
 10 #include<cstdio>
 11 #include<algorithm>
 12 #include<cmath>
 13 #include<cstring>
 14 #include<string>
 15 #include<map>
 16 #include<set>
 17 #include<queue>
 18 #include<vector>
 19 #include<stack>
 20 #include<cctype>
 21 #define fst first              
 22 #define sec second      
 23 #define lson l,m,rt<<1
 24 #define rson m+1,r,rt<<1|1
 25 #define ms(a,x) memset(a,x,sizeof(a))
 26 using namespace std;
 27 const double eps = 1E-8;
 28 const int dx4[4]={1,0,0,-1};
 29 const int dy4[4]={0,-1,1,0};
 30 typedef long long LL;
 31 const int inf = 0x3f3f3f3f;
 32 const int N=25;
 33 const double pi =acos(-1.0);
 34 int n;
 35 int dblcmp(double d)
 36 {
 37     return d<-eps?-1:d>eps;
 38 }
 39 struct point
 40 {
 41     double x,y;
 42     point(){}
 43     point(double _x,double _y):
 44     x(_x),y(-y){};
 45     void input()
 46     {
 47     scanf("%lf%lf",&x,&y);
 48     }
 49     point sub(point p)
 50     {
 51     return point(x-p.x,y-p.y);
 52     }
 53     double dot(point p)
 54     {
 55     return x*p.x+y*p.y;
 56     }
 57     double det(point p)
 58     {
 59     return x*p.y-y*p.x;
 60     }
 61     double distance(point p)
 62     {
 63     return hypot(x-p.x,y-p.y);
 64     }
 65 };
 66 
 67 struct circle
 68 {
 69     point p;
 70     double r;
 71     circle(){}
 72     circle(point _p,double _r):
 73     p(_p),r(_r){};
 74     void input()
 75     {
 76     p.input();
 77     scanf("%lf",&r);
 78     }
 79     double area()
 80     {
 81     return pi*r*r;
 82     }
 83 
 84     int relationcircle(circle v)
 85     {
 86     double d=p.distance(v.p);
 87     if (dblcmp(d-r-v.r)>0) return 5;
 88     if (dblcmp(d-r-v.r)==0) return 4;
 89     double l = fabs(r-v.r);
 90     if (dblcmp(d-r-v.r)<0&&dblcmp(d-l)>0) return 3;
 91     if (dblcmp(d-l)==0) return 2;
 92     if (dblcmp(d-l)<0) return 1;
 93     }
 94 
 95     double areacircle(circle v)
 96     {
 97     int rel = relationcircle(v);
 98     if (rel>=4) return 0.0;
 99     if (rel<=2) return min(area(),v.area());
100     double d=p.distance(v.p);
101     double hf=(r+v.r+d)/2.0;
102     double ss=2*sqrt(hf*(hf-r)*(hf-v.r)*(hf-d));
103     double a1=acos((r*r+d*d-v.r*v.r)/(2.0*r*d));
104     a1 = a1 *r*r;
105     double a2=acos((v.r*v.r+d*d-r*r)/(2.0*v.r*d));
106     a2 = a2*v.r*v.r;
107     return a1+a2-ss;
108     }
109 }cir[N];
110 
111 bool judge(double rr)
112 {
113     for ( int i = 1 ,j; i <= n ; i++)
114     {
115     circle tmp = cir[i];
116     tmp.r = rr;
117     for (  j = 1; j <= n ; j++)
118     {
119         double crossarea = tmp.areacircle(cir[j]);
120        // cout<<"cross_area:"<<crossarea<<endl;
121         if (crossarea<cir[j].area()/2.0)
122         break;
123     }
124     if (j==n+1) return true;
125     
126     }
127     return false;
128 
129 }
130 int main()
131 {
132   #ifndef  ONLINE_JUDGE 
133    freopen("in.txt","r",stdin);
134   #endif
135    int T;
136    scanf("%d",&T);
137    while ( T-- )
138     {
139     scanf("%d",&n);
140     for ( int i = 1  ; i <=  n ; i++) cir[i].input();
141     double l=0,r=1E5;
142     while (dblcmp(r-l)>0)
143     {
144        // cout<<"l:"<<l<<" r:"<<r<<endl;
145         double mid = (l+r)/2.0;
146         if (judge(mid))
147         r = mid;
148         else l=mid;
149 
150     }
151     printf("%.4f\n",r);
152 
153     }
154   
155    
156  #ifndef ONLINE_JUDGE  
157   #endif
158   fclose(stdin);
159     return 0;
160 }