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 <cstdio>

using namespace std;

int main() {
	double x1, y1, x2, y2, x3, y3;
	int n;
	cin >> n;

	for (int i = 0; i < n; i++) {
		cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
		double x = ((y1-y3)*(y1*y1-y2*y2+x1*x1-x2*x2)-(y1-y2)*(y1*y1-y3*y3+x1*x1-x3*x3))/(2*(y1-y3)*(x1-x2)-2*(y1-y2)*(x1-x3));
		double y = ((x1-x3)*(x1*x1-x2*x2+y1*y1-y2*y2)-(x1-x2)*(x1*x1-x3*x3+y1*y1-y3*y3))/(2*(x1-x3)*(y1-y2)-2*(x1-x2)*(y1-y3));

		printf("%.3f %.3f %.3f\n", x, y, sqrt(pow((x1 - x), 2) + pow((y1 - y), 2)));
	}
	return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <stdio.h>
#include <math.h>
using namespace std;
int main(){
	int n;
	cin>>n;
	for(int i=0;i<n;i++){
		double x1,y1,x2,y2,x3,y3,xp,yp,r;
		cin>>x1>>y1>>x2>>y2>>x3>>y3;
		xp=0;
		yp=0;
		double a=y2-y1,b=y3-y1,c=y2-y3,d=x2-x1,e=x3-x1;
		if(y1 != y2 && y1 != y3){
			xp=(c/2-e*(x1+x3)/2/b-d*(x2+x1)/2/a)/(-e/b+d/a);
			yp=-e/b*(xp-(x1+x3)/2)+(y1+y3)/2;
		}else if(y1==y2){
			xp=(x1+x2)/2;
			yp=-e/b*(xp-(x1+x3)/2)+(y1+y3)/2;
		}else if(y1==y3){
			xp=(x1+x3)/2;
			yp=-d/a*(xp-(x1+x2)/2)+(y1+y2)/2;
		}
		r = sqrt((x1-xp)*(x1-xp)+(y1-yp)*(y1-yp));
		printf("%.3lf %.3lf %.3lf\n",xp,yp,r);
	}
	return 0;
}

C++: #include <iostream>
#include <iomanip>
#include <algorithm>
#include <math.h>
using namespace std;

int main(){
	int n;
	double x1,x2,x3,y1,y2,y3;
	double a1,a2,b1,b2,c1,c2;
	double px,py;

	cin >> n;
	while(n > 0){
		cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
		n--;
	}
	
	a1 = 2 * (x2 - x1);
	b1 = 2 * (y2 - y1);
	c1 = x1 * x1 - x2 * x2 + y1 * y1 - y2 * y2;
	a2 = 2 * (x3 - x1);
	b2 = 2 * (y3 - y1);
	c2 = x1 * x1 - x3 * x3 + y1 * y1 - y3 * y3;
	
	px = (b1 * c2 - b2 * c1) / (a1 * b2 - a2 * b1);
	py = (c1 * a2 - c2 * a1) / (a1 * b2 - a2 * b1);
	
	cout << fixed << setprecision(3) << px << " " << fixed << setprecision(3) << py << " " << fixed << setprecision(3) << hypot(px - x1, py - y1) << endl;

	return 0;
}

C++: //#define _USE_MATH_DEFINES
#include <cmath>
#include <iostream>
#include <stdio.h>
//#include <stdlib.h>
//#include <iomanip>
//#include <vector>
//#include <string>
//#include <algorithm>
//#include <functional>
//#include <time.h>
//#include <sstream>
//#include <queue>

using namespace std;


int main(){

	int n;
	double ax, ay, bx, by, cx, cy;
	double A, B, C,S2;
	double x, y,r;

	cin >> n;

	while (n--){
		cin >> ax >> ay >> bx >> by >> cx >> cy;

		A = (bx - cx)*(bx - cx) + (by - cy)*(by - cy);
		B = (cx - ax)*(cx - ax) + (cy - ay)*(cy - ay);
		C = (bx - ax)*(bx - ax) + (by - ay)*(by - ay);
		S2 = A*(B + C - A) + B*(C + A - B) + C*(A + B - C);

		x = (A*(B + C - A)*ax + B*(C + A - B)*bx + C*(A + B - C)*cx) / S2;
		y = (A*(B + C - A)*ay + B*(C + A - B)*by + C*(A + B - C)*cy) / S2;

		r = sqrt((x - ax)*(x - ax) + (y - ay)*(y - ay));

		printf("%.3f %.3f %.3f\n", x, y, r);
	}
}

C++: #include <iostream>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <vector>

using namespace std;

int main(void){
	int num;
	cin >> num;
	vector<double> res_x, res_y, res_r;
	for (int i=1; i<=num; ++i){
		double x1, y1, x2, y2, x3, y3;
		cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
		double e1_2 = sqrt(pow((x2-x1), 2) + pow((y2-y1), 2));
		double e2_3 = sqrt(pow((x2-x3), 2) + pow((y2-y3), 2));
		double e3_1 = sqrt(pow((x3-x1), 2) + pow((y3-y1), 2));
		double theta = acos((e1_2*e1_2 + e2_3*e2_3 - e3_1*e3_1) / (2*e1_2*e2_3));
		//正弦定理により
		double r = e3_1 / (2*sin(theta));
		double a1 = 2*(x2-x1);
		double b1 = 2*(y2-y1);
		double c1 = x1*x1 - x2*x2 + y1*y1 -y2*y2;
		double a2 = 2*(x3-x1);
		double b2 = 2*(y3-y1);
		double c2 = x1*x1 - x3*x3 + y1*y1 - y3*y3;
		double x = (b1*x2 - b2*c1) / (a1*b2 - a2*b1);
		double y = (c1*a2 - c2*a1) / (a1*b2 - a2*b1);
		res_x.push_back(x);
		res_y.push_back(y);
		res_r.push_back(r);
	}
	for (int i=0; i<num; ++i){
		cout << fixed << setprecision(3) << res_x[i] << " " << res_y[i] << " " << res_r[i] << endl;
	}
	return 0;
}