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 "bits/stdc++.h"

#define REP(i,num) for(int i=0;i<(num);++i)
#define ALL(c) c.begin(),c.end()
#define PRINTALL(c) for(auto& x:c){cout<<x<<' ';}cout<<endl;
#define PAIRCOMP(c,comp) [](const pair<ll,ll>& lhs,const pair<ll,ll>& rhs){return lhs.c comp rhs.c;}

using namespace std;
using ll = long long;

constexpr ll atcoder_mod = 1e9+7;

template<typename T=int>
T in(){T x; cin >> x; return (x);}
template<typename T=int,typename C=vector<T>>
C vecin(int N){C x(N);REP(i,N){x[i]=in<T>();}return move(x);}

void vout(){cout << endl;}
template<typename Head,typename... Tail>
void vout(Head&& h,Tail&&... t){cout << ' ' << h;vout(forward<Tail>(t)...);}
void out(){cout << endl;}
template<typename Head,typename... Tail>
void out(Head&& h,Tail&&... t){cout << h;vout(forward<Tail>(t)...);}

int main(){
	//cin.tie(0);
	//ios::sync_with_stdio(false);
	
	int N=in();
	REP(i,N){
		double x1,y1,x2,y2,x3,y3;
		cin>>x1>>y1>>x2>>y2>>x3>>y3;

		double a=hypot(x2-x3,y2-y3);
		double b=hypot(x1-x3,y1-y3);
		double c=hypot(x2-x1,y2-y1);
		double coeff1 = a*a*(b*b+c*c-a*a);
		double coeff2 = b*b*(a*a+c*c-b*b);
		double coeff3 = c*c*(b*b+a*a-c*c);

		double x = (coeff1*x1+coeff2*x2+coeff3*x3)/(coeff1+coeff2+coeff3);
		if(abs(x)<=1e-7) x=0;
		double y = (coeff1*y1+coeff2*y2+coeff3*y3)/(coeff1+coeff2+coeff3);
		if(abs(y)<=1e-7) y=0;
		double r = hypot(x-x1,y-y1);
		
		printf("%.3lf %.3lf %.3lf\n",round(x*1000)/1000,round(y*1000)/1000,round(r*1000)/1000);
	}

	return 0;
}

C++: //#Circumscribed Circle of a Triangle

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
using namespace std;

int main() {
	double x1, y1, x2, y2, x3, y3;
	double px, py, r;
	int n;
	cin >> n;
	for(int i = 0; i < n; i++) {
		cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
		px = ((x2*x2+y2*y2-x1*x1-y1*y1)*(y1-y3) - (x3*x3+y3*y3-x1*x1-y1*y1)*(y1-y2)) / (-2*((x1-x2)*(y1-y3) - (x1-x3)*(y1-y2)));
		py = ((x2*x2+y2*y2-x1*x1-y1*y1)*(x1-x3) - (x3*x3+y3*y3-x1*x1-y1*y1)*(x1-x2)) / (-2*((y1-y2)*(x1-x3) - (y1-y3)*(x1-x2)));
		r = sqrt((x1-px)*(x1-px) + (y1-py)*(y1-py));
		
		printf("%.3f %.3f %.3f\n", px, py, r);
	}
	return 0;
}

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

using namespace std;

double sq(double x) {return x*x;}

void solve()
{
	double x1,y1,x2,y2,x3,y3;
	cin>>x1>>y1>>x2>>y2>>x3>>y3;
	double a,b,c,d,e,f;
	a = x2-x1; b = y2- y1;
	a*=2; b*= 2;
	c = sq(x2)-sq(x1)+sq(y2)-sq(y1);
	d = x3-x1; e = y3- y1;
	d *=2; e *= 2;
	f = sq(x3)-sq(x1)+sq(y3)-sq(y1);
    double det = a*e - b * d;
    double x = 1 / det * (c * e - b * f);
    double y = 1 / det * (f * a - c * d);
    if(x < 1e-5 && -1e-5 < x) x = 0.0;
    if(y < 1e-5 && -1e-5 < y) y = 0.0;
	double r = sqrt(sq(x - x1) + sq(y - y1));

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

int main(){

	int t;
	cin >> t;
    while(t--){
		solve();
	}

	return 0;
}

C++: #include<iostream>
#include<cstdio>
#include<algorithm>
#include<climits>
#include<queue>
#include<map>
#include<set>
#include<vector>
#include<list>
#include<stack>
#include<cstring>
#include<string>
#include<cmath>
using namespace std;

struct Coor{
	double x,y;
};

struct Ans2{
	double l,m;
};

struct Ans3{
	double l,m,n;
	Ans3(Ans2 &a){
		l=a.l; m=a.m;
	}
};

Ans2 solve2(double l[2],double m[2],double n[2]){
	/*for(int i=0;i<2;i++){
		printf("(%lfl)+(%lfm)+n = (%lf)\n",l[i],m[i],n[i]);
	}*/
	Ans2 ans;
	double a,b;
	a = l[0]*m[1]-l[1]*m[0]; b = n[0]*m[1]-n[1]*m[0];
	ans.l = b/a;
	//printf("%lfx = %lf\n",a,b);
	a = m[0]*l[1]-m[1]*l[0]; b = n[0]*l[1]-n[1]*l[0];
	ans.m = b/a;
	//printf("%lfy = %lf\n",a,b);
	return ans;
}

Ans3 solve3(double l[3],double m[3],double n[3]){
	double _l[2],_m[2],_n[2];
	_l[0] = l[0]-l[1]; _l[1] = l[0]-l[2];
	_m[0] = m[0]-m[1]; _m[1] = m[0]-m[2];
	_n[0] = n[0]-n[1]; _n[1] = n[0]-n[2];
	Ans3 ans = Ans3(solve2(_l,_m,_n));
	ans.n = n[0]-(l[0]*ans.l+m[0]*ans.m);
	return ans;
}

int main(){
	int N;
	cin>>N;
	for(int i=0;i<N;i++){
		Coor in[3];
		double l[3],m[3],n[3];
		for(int i=0;i<3;i++){
			cin>>in[i].x>>in[i].y;
			l[i] = in[i].x;
			m[i] = in[i].y;
			n[i] = -(in[i].x*in[i].x+in[i].y*in[i].y);
			//printf("(%lfl)+(%lfm)+n = (%lf)\n",l[i],m[i],n[i]);
		}
		Ans3 ans3 = solve3(l,m,n);
		//printf("l = %lf, m = %lf, n = %lf\n",ans3.l,ans3.m,ans3.n);
		double r = sqrt(-(ans3.n-ans3.l/2*ans3.l/2-ans3.m/2*ans3.m/2));
		printf("%.3lf %.3lf %.3lf\n",-ans3.l/2,-ans3.m/2,r);
	}
}