Go: package main

import (
	"bufio"
	"fmt"
	"io"
	"math"
	"os"
	"strconv"
	"strings"

)


func main() {
	solve(os.Stdin, os.Stdout)
}

type ReaderEx struct {
	baseScanner *bufio.Scanner
	words       []string
	nextWordIdx func() int
	initWordIdx func(int)
}

func NewScannerEx(stdin io.Reader) *ReaderEx {
	var this ReaderEx
	var idx int
	var wordsCnt int
	this.baseScanner = bufio.NewScanner(stdin)
	this.baseScanner.Buffer(make([]byte, 0), 1E+11)
	this.nextWordIdx = func() int {
		cur := idx
		idx = (idx + 1) % wordsCnt
		return cur
	}
	this.initWordIdx = func(wc int) {
		idx = 0
		wordsCnt = wc
	}
	return &this
}

func (me *ReaderEx) Scan(doSplit bool) (isScanned bool) {
	isScanned = me.baseScanner.Scan()
	if doSplit {
		me.words = strings.Fields(me.baseScanner.Text())
	} else {
		me.words = []string{me.baseScanner.Text()}
	}
	me.initWordIdx(len(me.words))
	return
}

func (me *ReaderEx) nextBytes() []byte {
	return []byte(me.words[me.nextWordIdx()])
}
func (me *ReaderEx) nextString() string {
	return me.words[me.nextWordIdx()]
}

type StringArray []string

func (me *ReaderEx) nextStringArray() StringArray {
	return me.words[me.nextWordIdx():]
}

func (me StringArray) toStrings() []string {
	return me
}

func (me StringArray) toInts() []int {
	strValues := me.toStrings()
	values := make([]int, len(strValues))
	for i, v := range strValues {
		n, err := strconv.Atoi(v)
		if err != nil {
			panic(err)
		}
		values[i] = n
	}
	return values
}
func (me *ReaderEx) nextInt() int {
	n, err := strconv.Atoi(me.words[me.nextWordIdx()])

	defer func() {
		if err != nil {
			panic(fmt.Sprintf("getInt(%d)", n))
		}
	}()
	return n
}

func pow(x, y, mod int) (ans int) {

	ans = 1
	for bit := 1 << uint(math.Floor(math.Log2(float64(y)))); ; bit >>= 1 {
		if y&bit != 0 {
			ans *= x
			if mod > 0 {
				ans %= mod
			}
		}
		if bit <= 1 {
			return
		}
		ans *= ans
		if mod > 0 {
			ans %= mod
		}
	}
}

type factType struct {
	prime int
	count int
}

func fact(n int) (facts []*factType) {

	for i := 2; i*i <= n; i++ {
		if n%i == 0 {
			fa := factType{prime: i}
			for n%fa.prime == 0 {
				n /= fa.prime
				fa.count++
			}
			facts = append(facts, &fa)
		}
	}
	if n > 1 {
		facts = append(facts, &factType{prime: n, count: 1})
	}
	return facts
}
func dec2bin(n int) (ret []bool) {
	for bit := 1 << uint(math.Floor(math.Log2(float64(n)))); ; bit >>= 1 {
		ret = append(ret, n&bit != 0)

		if bit <= 1 {
			return
		}
	}

}

func abs(v int) int {
	if v < 0 {
		v = -v
	}
	return v
}

func b2i(b bool) (i int) {
	if b {
		i = 1
	} else {
		i = 0
	}
	return
}

func solve(stdin io.Reader, stdout io.Writer) {

	r := NewScannerEx(stdin)
	r.Scan(true)
	n := r.nextInt()

	type Vec struct {
		x, y float64
	}
	vec := func(a, b Vec) Vec { return Vec{b.x - a.x, b.y - a.y} }
	unv := func(a Vec) Vec { return Vec{-a.y, a.x} }
	cdot := func(a, b Vec) float64 { return a.x*b.x + a.y*b.y }
	times := func(t float64, a Vec) Vec { return Vec{t * a.x, t * a.y} }
	add := func(a, b Vec) Vec { return Vec{a.x + b.x, a.y + b.y} }
	for i := 0; i < n; i++ {

		r.Scan(true)
		nextFloat64 := func() (ret float64) { fmt.Sscanf(r.nextString(), "%f", &ret); return }
		a1, a2, a3 := Vec{nextFloat64(), nextFloat64()}, Vec{nextFloat64(), nextFloat64()}, Vec{nextFloat64(), nextFloat64()}
		unv23 := unv(vec(a2, a3))
		v12 := vec(a1, a2)
		v31 := vec(a3, a1)
		s := cdot(v12, v31) / 2 / cdot(v12, unv23)
		c := add(times(.5, add(a2, a3)), times(s, unv23))
		v1c := vec(a1, c)
		fmt.Fprintf(stdout, "%.3f %.3f %.3f\n", c.x, c.y, math.Sqrt(v1c.x*v1c.x+v1c.y*v1c.y))
	}
}

C++: #include<iostream>
#include<stdio.h>
#include<math.h>
using namespace std;
int main()
{
    double x1,y1,x2,y2,x3,y3;
    int n;cin>>n;
    while(n--)

    {
        cin>>x1>>y1>>x2>>y2>>x3>>y3;
         double  d1 = x1*x1+y1*y1;
      double  d2 = x2*x2+y2*y2;
      double  d3 = x3*x3+y3*y3;
      double  u = 0.5/(x1*y2-x2*y1+x2*y3-x3*y2+x3*y1-x1*y3);
      double  xp = u*(d1*y2-d2*y1+d2*y3-d3*y2+d3*y1-d1*y3);
      double  yp = u*(x1*d2-x2*d1+x2*d3-x3*d2+x3*d1-x1*d3);
      double  r = sqrt((xp-x1)*(xp-x1)+(yp-y1)*(yp-y1));
      printf("%.3f %.3f %.3f\n",xp,yp,r);
    }



    return 0;
}

C++: #include <iostream>
#include <stdio.h>
#include <string>
#include <queue>
#include <cmath>

#define int64 long long int

using namespace std;

int main()
{
	int n;
	double x1,y1,x2,y2,x3,y3,x,y,r;
	double det,a1,b1,a2,b2,c1,c2;
	cin >> n;
	for(int i=0; i<n; i++){
		cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
		a1 = 2 * (x1 - x2), b1 = 2 * (y1 - y2);
		a2 = 2 * (x2 - x3), b2 = 2 * (y2 - y3);
		det = a1 * b2 - a2 * b1;
		c1 = (x1*x1 - x2*x2) + (y1*y1 - y2*y2);
		c2 = (x2*x2 - x3*x3) + (y2*y2 - y3*y3);
		x = (a1 * c1 + b1 * c2) / det;
		y = (a2 * c1 + b2 * c2) / det;
		r = sqrt((x - x1)*(x - x1) + (y - y1)*(y - y1));
		if(fabs(x) < 1e-6) x = 0.0;
		if(fabs(y) < 1e-6) y = 0.0;
		printf("%.3f %.3f %.3f\n", x, y, r);
	}
	return 0;
}

C++: //
//  main.cpp
//  adsfdsgsg
//
//  Created by h3037175 on 2017/07/31.
//  Copyright ?? 2017??´ h3037175. All rights reserved.
//

#include <iostream>
#include <cstdio>
#include <math.h>
#include<algorithm>
#include <utility>
#define nan -100000
using namespace std;
bool isY(double y1,double y2,double y3){
    if(y1==y2 || y1==y3 || y2==y3 ){
        return true;
    }
    else {
        return false;
    }
}
bool isX(double x1,double x2,double x3){
    if(x1==x2 || x1==x3 || x2==x3 ){
        return true;
    }
    else {
        return false;
    }
}
int main() {
    int n;
    double a,x1,x2,x3,y1,y2,y3,px,py,r;
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>x1>>y1>>x2>>y2>>x3>>y3;
        double X[3]={x1,x2,x3},Y[3]={y1,y2,y3};
        sort(X,X+3);sort(Y,Y+3);
        px=(X[2]-X[0])/2;
        py=(Y[2]-Y[0])/2;
            r=sqrt(px*px+py*py);
        printf("%.3f %.3f %.3f",px,py,r);
        cout<<endl;
    }
    return 0;
}
//3633
/*
 
 
 
 
                                  /
                                 /|
                                / |
                               /  |
                              /   |
                             /    |
                            / |   |
                           /  |   |
                          /   |   |
                         /    |   |
                        /     |   |
                       /      |   |
                      /       |   |
                     /-------------








*/

C++: #include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <cmath>

using namespace std;

int main()
{
	int n;
	scanf("%d", &n);
	for (int i = 0; i < n; ++i)
	{
		double x[3], y[3];
		for (int j = 0; j < 3; ++j)
			scanf("%lf %lf", x+j, y+j);
		
		double a[2], b[2];
		for (int j = 0; j < 2; ++j)
		{
			a[j] = -(x[2]-x[j])/(y[2]-y[j]);
			b[j] = (y[2]+y[j] - (x[2]+x[j])*a[j])/2;
		}
		double px = (b[0]-b[1])/(a[1]-a[0]);
		double py = a[0] * px + b[0];
		double r = sqrt((px-x[0])*(px-x[0])+(py-y[0])*(py-y[0]));
		printf("%f %f %f\n", px, py, r);
	}

	return 0;
}

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

using namespace std;

int n;
int tx1, ty1, tx2, ty2, tx3, ty3;

int main()
{
	cin >> n;
	for(int i=0; i<n; i++)
	{
		cin >> tx1 >> ty1;
		cin >> tx2 >> ty2;
		cin >> tx3 >> ty3;

		double mx1 = (tx1 + tx2) / 2.0;
		double my1 = (ty1 + ty2) / 2.0;
		double a1 = (double)(tx2 - tx1);
		double b1 = (double)(ty2 - ty1);
		double c1 = a1 * mx1 + b1 * my1;

		double mx2 = (tx2 + tx3) / 2.0;
		double my2 = (ty2 + ty3) / 2.0;
		double a2 = (double)(tx3 - tx2);
		double b2 = (double)(ty3 - ty2);
		double c2 = a2 * mx2 + b2 * my2;

		double det = a1 * b2 - a2 * b1;
		
		double cx = (b2 * c1 - a2 * c2) / det;
		double cy = (-a2 * c1 + a1 * c2) / det;
		
		double dx = cx - tx1;
		double dy = cy - ty1;
		double r = sqrt(dx*dx + dy*dy);
		
		printf("%.3f %.3f %.3f\n", cx, cy, r);
	}
}