Go: package main

import (
	"fmt"
	"math"
)

func main() {
	var num int
	fmt.Scan(&num)
	for i := 0; i < num; i++ {
		var x1, y1, x2, y2, x3, y3 float64
		fmt.Scanf("%f%f%f%f%f%f", &x1, &y1, &x2, &y2, &x3, &y3)

		a := 2 * (x2 - x1)
		b := 2 * (y2 - y1)
		c := 2 * (x3 - x1)
		d := 2 * (y3 - y1)
		e := x2*x2 - x1*x1 + y2*y2 - y1*y1
		f := x3*x3 - x1*x1 + y3*y3 - y1*y1

		// 直線1: ax + by - e = 0
		// 直線2: cx + dy - f = 0
		px := (d*e - b*f) / (a*d - b*c)
		py := (c*e - a*f) / (b*c - a*d)
		r := math.Sqrt((px-x1)*(px-x1) + (py-y1)*(py-y1))
		fmt.Printf("%.3f %.3f %.3f\n", px, py, r)
	}
}

C++: /* {{{ Shinobu kawaii */
/*
  ______   __        _                  __                 
.' ____ \ [  |      (_)                [  |                
| (___ \_| | |--.   __   _ .--.   .--.  | |.--.   __   _   
 _.____`.  | .-. | [  | [ `.-. |/ .'`\ \| '/'`\ \[  | | |  
| \____) | | | | |  | |  | | | || \__. ||  \__/ | | \_/ |, 
 \______.'[___]|__][___][___||__]'.__.'[__;.__.'  '.__.'_/ 
                                                           
*/
/* }}} */
/* include {{{ */
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <iostream>
#include <vector>
#include <string>
#include <sstream>
#include <algorithm>
#include <utility>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <functional>
using namespace std;
/* }}} */

// #define int long long

/* cpp template {{{ */
/* short */
#define pb push_back
#define mp make_pair
#define print(x) cout << x << '\n'
#define Fi first
#define Se second

/* REPmacro */
#define REPS(i, a, n) for (int i = (a); i < (n); i++)
#define REP(i, n) for (int i = 0; i < (n); i++)
#define RREP(i, n) for (int i = 1; i <= (n); i++)
#define DEPS(i, a, n) for (int i = (a); i >= n; i--)
#define DEP(i, n) for (int i = (n); i >= 0; i--)

/* typedef */
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<vector<int> > vii;
typedef pair<int, int> pii;

/* const */
const int INF = 999999999;
const int dx[] = {0, 1, 0, -1, 1, -1, 1, -1}, dy[] = {1, 0, -1, 0, 1, -1, -1, 1};

/* func */
inline bool is_uruu(int y) {return (y % 4 == 0 && (y % 100 != 0 || y % 400 == 0));}
inline bool inside(int y, int x, int H, int W) {return (y >= 0 && x >= 0 && y < H && x < W);}

/* }}} */

signed main()
{
  cin.tie(0);
  //ios::sync_with_stdio(false);

  int n;
  cin >> n;

  while (n--){
    double x1, y1, x2, y2, x3, y3;
    cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
    double xA = x2 - x1, yA = y2 - y1, 
           xB = x3 - x1, yB = y3 - y1;
    double s = (xA * xB + yA * yB - xB * xB - yB * yB) / (xA * yB - xB * yA);
    s /= 2;
    double xO = xA / 2 + s * yA,
           yO = yA / 2 - s * xA;
    double r = sqrt(fabs(x1 - xO) * fabs(x1 - xO) + fabs(y1 - yO) * fabs(y1 - yO));
    printf("%.3f %.3f %.3f\n", xO, yO, r);
  }

  return (0);
}

C++: #include <iostream>
#include <cmath>

using namespace std;
typedef struct { double x; double y;} point;
 
point getCircumcenter(point a, point b, point c)
{
    double A1 = 2.0f * ( b.x - a.x );
    double B1 = 2.0f * ( b.y - a.y );
    double C1 = pow(a.x,2)-pow(b.x,2) + pow(a.y,2)-pow(b.y,2);
    double A2 = 2.0f * ( c.x - a.x );
    double B2 = 2.0f * ( c.y - a.y );
    double C2 = pow(a.x,2)-pow(c.x,2) + pow(a.y,2)-pow(c.y,2);
    double X = (B1 * C2 - B2 * C1) / (A1 * B2 - A2 * B1);
    double Y = (C1 * A2 - C2 * A1) / (A1 * B2 - A2 * B1);
	point P;
	P.x=X;
	P.y=Y;
    return P;
}

double getTwoPointDictance(point a, point b)
{
	return fabs(sqrt(pow((a.x-b.x),2)+pow((a.y-b.y),2)));
}
double AntiMinusZero(double n)
{
	if(n==0)
	{
		return 0.0f;
	}
	return n;
}

int main()
{
    int n;
    cin>>n;
    point a,b,c;
    while(n--)
	{
        cin>>a.x>>a.y>>b.x>>b.y>>c.x>>c.y;
        point ans = getCircumcenter(a,b,c);
        printf("%.3lf %.3lf %.3lf\n", AntiMinusZero(ans.x), AntiMinusZero(ans.y), getTwoPointDictance( a, ans));
    }
}

C++: #include<bits/stdc++.h>
using namespace std;

struct Point{double x, y;};

Point center2(Point p1, Point p2, Point p3){
	Point p;
	if(p1.y == p2.y){
		p.x = (p1.x + p2.x) / 2.0;
	}else if(p2.y == p3.y){
		p.x = (p2.x + p3.x) / 2.0;
	}
	p.y = p.x - (p2.x + p3.x) / 2.0;
	p.y *= -(p3.x - p2.x) / (p3.y - p2.y);
	p.y += (p2.y + p3.y) / 2.0;
	return p;
}

Point center(Point p1, Point p2, Point p3){
	if(p1.y == p2.y || p2.y == p3.y) return center2(p1, p2, p3);
	Point p;
	p.x = 0.0;
	p.x += (p3.y - p1.y) / 2.0;
	p.x -= (p2.x * p2.x - p1.x * p1.x) / (2.0 * (p2.y - p1.y));
	p.x += (p3.x * p3.x - p2.x * p2.x) / (2.0 * (p3.y - p2.y));
	p.x /= ((p3.x - p2.x) / (p3.y - p2.y) - (p2.x - p1.x) / (p2.y - p1.y));
	p.y = p.x - (p2.x + p3.x) / 2.0;
	p.y *= -(p3.x - p2.x) / (p3.y - p2.y);
	p.y += (p2.y + p3.y) / 2.0;
	return p;
}

double rounding(double d){
	if(d - (int)floor(d) < 0.5) return floor(d);
	else return ceil(d);
}

int main(){
	int n;
	Point p1, p2, p3;
	Point p;
	double r;
	scanf("%d", &n);
	for(int i = 0; i < n; i++){
		scanf("%lf %lf %lf %lf %lf %lf", &p1.x, &p1.y, &p2.x, &p2.y, &p3.x, &p3.y);
		p = center(p1, p2, p3);
		r = sqrt((p.x - p1.x) * (p.x - p1.x) + (p.y - p1.y) * (p.y - p1.y));
		printf("%.3lf %.3lf %.3lf\n", rounding(p.x * 1000.0) / 1000.0, rounding(p.y * 1000.0) / 1000.0, rounding(r * 1000.0) / 1000.0);
	}
	return 0;
}

C++: /* Karen {{{
  ___  ____
 |_  ||_  _|
   | |_/ /    ,--.   _ .--.  .---.  _ .--.
   |  __'.   `'_\ : [ `/'`\]/ /__\\[ `.-. |
  _| |  \ \_ // | |, | |    | \__., | | | |
 |____||____|\'-;__/[___]    '.__.'[___||__]
}}} */
/* include {{{ */
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <cmath>
#include <cstdio>
#include <string>
#include <vector>
#include <complex>
#include <iostream>
#include <algorithm>

using namespace std;

/*  }}} */
/* cpp template {{{*/


#define endl '\n'
#define REP(i, n) for (int i = 0; i < (n); i++)
#define REPS(i, a, n) for (int i = (a); i < (n); i++)
#define RREP(i, n) for (int i = 1; i <= (n); i++)
#define X real()
#define Y imag()
#define EQ(n,m) (abs((n)-(m)) < EPS)

typedef double D;      // ??§?¨?????????????double???long double?????????
typedef long long ll;
typedef long double lb;
typedef complex<D> P;  // Point
typedef pair<P, P> L;  // Line
typedef vector<P> VP;
typedef vector<int> vi;
typedef vector<vector<int> > vii;
typedef pair<int, int> pii;
typedef pair<int, string> pis;
typedef pair<string, int> psi;

inline bool inside(int y, int x, int H, int W){return (y >= 0 && x >= 0 && y < H && x < W);}
inline int in() {int x; std::cin >> x; return x;}

template <typename T>
void print(std::vector<T>& v, char c = ' ') {
  REP(i, v.size()) {
    if (i != 0) std::cout << c;
    std::cout << v[i];
  }
  std::cout << endl;
}
template <typename T>
void print(T x) {
  std::cout << x << '\n';
}

/* ?????° */
const ll MOD = 1e9 + 7;
const ll INF = 1e9 + 9;
const D EPS  = 1e-9;
const int dx[] = {0, 1, 0, -1, 1, -1, 1, -1};
const int dy[] = {1, 0, -1, 0, 1, -1, -1, 1};


/* }}} */

D cross(P a, P b) {
  return (conj(a)*b).Y;
}

P crosspointLL(P a1, P a2, P b1, P b2) {
  D d1 = cross(b2-b1, b1-a1);
  D d2 = cross(b2-b1, a2-a1);
  if (EQ(d1, 0) && EQ(d2, 0)) return a1;  // same line
  if (EQ(d2, 0)) throw "kouten ga nai";   // ???????????????
  return a1 + d1/d2 * (a2-a1);
}

P circumcenter(P a, P b, P c) {
  a = (a-c)*0.5;
  b = (b-c)*0.5;
  return c + crosspointLL(a, a*P(1,1), b, b*P(1,1));
}

int main()
{
  cin.tie(0);
  ios::sync_with_stdio(false);

  int x = in();
  
  for (int i = 0; i < x; i++){
    D a1, a2, b1, b2, c1, c2;
    cin >> a1 >> a2 >> b1 >> b2 >> c1 >> c2;
    P p = circumcenter( P(a1, a2), P(b1, b2), P(c1, c2));
    D r = sqrt(pow(a1 - p.X, 2) + pow(a2 - p.Y, 2));
    printf("%.3f %.3f %.3f", p.X, p.Y, r);

    cout << endl;
  }
  return (0);
}