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 <queue>
#include <stack>
#include <vector>
#include <stdio.h>
#include <algorithm>
#include <string.h>
#include <string>
#include <complex>
using namespace std;

#define rep(i,n) for(int i=0;i<int(n);++i)
typedef complex<double> P;
typedef long long ll;

int n;
double x[3],y[3];
double px,py,r;

double in_pro(P a,P b){
	return a.real()*b.real()-a.imag()*b.imag();
}

double squ(P a, P b){
	double s = (a.real()*b.imag()-a.imag()*b.real())/2;
	if(s<0) s*=-1;
	return s;
}


int main(){
	cin>>n;
	rep(i,n){
		rep(i,3){
			cin>>x[i]>>y[i];
		}
		P a(x[1]-x[0],y[1]-y[0]), b(x[2]-x[0],y[2]-y[0]);
		double alen = abs(a),blen = abs(b);
		alen*=alen; blen*=blen;
		double inp = in_pro(a,b);
		double s = squ(a,b);
		//P I=(inp-alen*alen)/(inp*inp-alen*alen)*a + (inp-blen*blen)/(inp*inp-blen*blen)*b;
		P I=(blen*(alen-inp)*a + alen*(blen-inp)*b)/((alen*blen-inp*inp)*2);
		//cout<<alen<<" "<<blen<<" "<<inp<<endl;
		
		printf("%0.3f %0.3f %0.3f\n",I.real()+x[0],I.imag()+y[0],abs(I));
		}
	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;
		double a=x2-x1,b=y2-y1,c=x3-x1,d=y3-y1;
		if(a==0){
			xp = c/2+d/2/c-b*d/2/c;
			yp = b/2;
		}else if(b==0){
			xp = a/2;
			yp = -a*c/2/d+c*c/2/d+d/2;
		}else if(c==0){
			xp = a/2+b/2/a-d*b/2/a;
			yp = d/2;
		}else if(d==0){
			xp = c/2;
			yp = -a*c/2/b+a*a/2/b+b/2;
		}else{
			xp = (d*(a*a+b*b)-b*(c*c+d*d))/(a*d-b*c)/2;
			yp = -a*xp/b+a*a/2/b+b/2;
		}
		r = sqrt((x1-xp)*(x1-xp)+(y1-yp)*(y1-yp));
		printf("%.3lf %.3lf %.3lf\n",xp,yp,r);
	}
	return 0;
}

C++: #include<complex.h>
#include<stdio.h>
#define F(a,b,c) acos((b*b+c*c-a*a)/2/b/c)
#define G(a,b) pow(a-b,2)
#define H(a,b,c,d) sqrt(G(a,b)-G(c,d))
int main(){
	typedef double D;
	int n;D d,e,f,g,h,i;
	for(scanf("%d",&n);n--;){
		scanf("%lf%lf%lf%lf%lf%lf",&d,&g,&e,&h,&f,&i);
		//complex a(d,g),b(e,h),c(f,i);
		D /*A=abs(b-c),B=abs(c-a),C=abs(a-b),*/
		A=H(e,h,d,g),B=H(f,i,d,g),C=(d,g,e,h),
		L=F(A,B,C),s=sin(2*L),t=sin(2*F(B,C,A)),u=sin(2*F(C,A,B)),v=s+t+u;
		printf("%.3f %.3f %.3f\n",(d*s+e*t+f*u)/v,(g*s+h*t+i*u)/v,A/sin(L)/2);
	}
}

C++: #include<iostream>
#include<math.h>
#include<stdio.h>
using namespace std;
int main() {
	double x1, x2, x3, px, y1, y2, y3, py,r;
	int n;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
		if (y1 == y2) {
			px = (x1 + x2) / 2;
			py = (x1 - x3)*(x2 - x3) / (2 * (y3 - y1)) + (y1 + y3) / 2;
		}
		else if (y1 == y3) {
			px = (x1 + x3) / 2;
			py = (x1 - x2)*(x3 - x2) / (2 * (y2 - y1)) + (y1 + y2) / 2;
		}
		else {
			px = ((x1*x1 - x2*x2) / (y2 - y1) - (x1*x1 - x3*x3) / (y3 - y1) + y3 - y2) / (2 * ((x1 - x2) / (y2 - y1) - (x1 - x3) / (y3 - y1)));
			py = (px - (x1 + x2) / 2)*(x1 - x2) / (y2 - y1) + (y1 + y2) / 2;
		}
		r = sqrt((px - x1)*(px - x1) + (py - y1)*(py - y1));
		px = double(int(1000 * px + 0.5)) / 1000;
		py = double(int(1000 * py + 0.5)) / 1000;
		r = double(int(1000 * r + 0.5)) / 1000;
		printf("%.3f %.3f %.3f\n", px, py, r);
	}
	return 0;
}