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 <stdio.h>
#include <math.h>
#define NOT_E 200

double cequal(double *a,double *b,double *c,double *aa,double *bb,double *cc);
double equal(double a,double b,double c,double aa,double bb,double cc);
double answer(double x1,double x2,double y1,double y2,double *a,double *b);
int swap(double *a,double *b);

int main(){
	int i,cnt;
	double x1,x2,x3,y1,y2,y3,xp,yp/*¦*/,a1,a2,b1,b2,xm1,ym1,xm2,ym2,r;
	
	scanf("%d",&cnt);
	for(i=0;i<cnt;i++){
		
		scanf("%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3);
		
		xp=equal(y1,y2,y3,x1,x2,x3);
		yp=equal(x1,x2,x3,y1,y2,y3);
		
		
		if (xp==NOT_E || yp==NOT_E){
			if(xp==NOT_E){
				cequal(&x1,&x2,&x3,&y1,&y2,&y3);
			}else if(yp==NOT_E){
				cequal(&y1,&y2,&y3,&x1,&x2,&x3);
			}
			answer(x3,x2,y3,y2,&a1,&b1);
			answer(x3,x1,y3,y1,&a2,&b2);
			xp=(b2-b1)/(a1-a2);
			yp=a1*xp+b1;
			
		}
		
		if(xp==x1){
			r=sqrt((xp-x1)*(xp-x1));
		}else if(yp==y2){
			r=sqrt((yp-y1)*(yp-y1));
		}else{
			r=sqrt((xp-x1)*(xp-x1)+(yp-y1)*(yp-y1));
		}
		
		printf("%.3f %.3f %.3f\n",xp,yp,r);

	}
	return 0;
}
			
			
			
			

double cequal(double *a,double *b,double *c,double *aa,double *bb,double *cc){	/*a1=a2,a3ÆÈéæ¤ÉÀÑÖ¦é*/
	if(*a==*b){
	}else if (*b==*c){
		swap(a,c);
		swap(aa,cc);
	}else if (*c==*a){
		swap(b,c);
		swap(bb,cc);
	}else{
		return NOT_E;
	}
	
	return (*a+*b)/2;
}


double equal(double a,double b,double c,double aa,double bb,double cc){	/*ÀÑÖ¦È¢*/
	if(a==b){
	}else if (b==c){
		swap(&a,&c);
		swap(&aa,&cc);
	}else if (c==a){
		swap(&b,&c);
		swap(&bb,&cc);
	}else{
		return NOT_E;
	}
	return (aa+bb)/2;
}



double answer(double x1,double x2,double y1,double y2,double *a,double *b){	/*(x1,y1)Æ(x2,y2)Ì¼ñªüy=ax+bÌa,bð|C^ÅÔ·*/
	double xm,ym;
	*a=(y2-y1)/(x1-x2);
	xm=(x2+x1)/2;
	ym=(x2+y1)/2;
	*b=ym-*a*xm;
	return 0;
}

int swap(double *a,double *b){
	double temp;
	temp=*a;
	*a=*b;
	*b=*a;
	return 0;
}
	/*
	a2=(y1-y3)/(x3-x1);
	xm2=(x1+x3)/2;
	ym2=(x1+y3)/2;
	b2=ym2-a3*xm2;*/

C++: #include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;

int main(){
	int n;
	double x1,y1,x2,y2,x3,y3,x1_2,x1_3,y1_2,y1_3,z1_2,z1_3,a,b,c,r;
	while(cin >> n){
		for(int i = 0;i < n;++i){
			cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
			z1_2 = (((x1 * x1) + (y1 * y1)) * -1) - (((x2 * x2) + (y2 * y2)) * -1);
			z1_3 = (((x1 * x1) + (y1 * y1)) * -1) - (((x3 * x3) + (y3 * y3)) * -1);
			x1_2 = x1 - x2;
			x1_3 = x1 - x3;
			y1_2 = y1 - y2;
			y1_3 = y1 - y3;
			a = ((y1_2 * z1_3) - (y1_3 * z1_2)) / ((y1_2 * x1_3) - (y1_3 * x1_2)) * -1;
			b = ((x1_2 * z1_3) - (x1_3 * z1_2)) / ((x1_2 * y1_3) - (x1_3 * y1_2)) * -1;
			c = ((x1 * x1) + (y1 * y1) + (a * x1) + (b * y1)) * -1;
			r = sqrt(c + (a * a) + (b * b));
			printf("%.3f %.3f %.3f\n",a / 2.0,b / 2.0,r);
		}
	}
	return 0;
}

C++: #include <iostream>
#include <cmath>
#include <cstdio>
using namespace std;

void swap(double &x,double &y){
	double t;
	t=x;
	x=y;
	y=t;
}

double cut4(double x){
	double temp=x*pow(10,3);
	temp=double(int(temp+0.5));
	return temp*pow(10,-3);
}

int main(){
	int n;
	double x1,x2,x3,y1,y2,y3,px,py;
	double a,b,c,d,r;
	cin>>n;
	for(int i=0;i<n;i++){
		cin>>x1>>y1>>x2>>y2>>x3>>y3;
		if(x1==x2){
			swap(x2,x3);
			swap(y2,y3);
		}else if(x2==x3){
			swap(x1,x2);
			swap(y1,y2);
		}
		a=(y2-y1)/(x2-x1);
		c=(y3-y2)/(x3-x2);
		if(a&&c){
			a=-1/a;
			c=-1/c;
			b=(y1+y2)/2-a*(x1+x2)/2;
			d=(y2+y3)/2-c*(x2+x3)/2;
			px=(b-d)/(c-a);
			py=(b*c-a*d)/(c-a);
		}else if(!a){
			c=-1/c;
			d=(y2+y3)/2-c*(x2+x3)/2;
			px=(x1+x2)/2;
			py=c*(x1+x2)/2+d;
		}else if(!c){
			a=-1/a;
			b=(y1+y2)/2-a*(x1+x2)/2;
			px=(x2+x3)/2;
			py=a*(x2+x3)/2+b;
		}

		r=sqrt((px-x1)*(px-x1)+(py-y1)*(py-y1));
		
		printf("%.3lf %.3lf %.3lf\n",cut4(px),cut4(py),cut4(r));
	}
	return 0;
}