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++: //
//  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 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=2/(X[2]-X[0]);
        py=2/(Y[2]-Y[0]);
        if(isY(y1,y2,y3) || isX(x1,x2,x3)){
            int a;
            a=px*px+py*py;
            r=sqrt(a);
        }
        else{
            while(1){
                
            }
        }
        printf("%.3f %.3f %.3f",px,py,r);
        cout<<endl;
    }
    return 0;
}
//3633
/*
 
 
 
 
                                  /
                                 /|
                                / |
                               /  |
                              /   |
                             /    |
                            / |   |
                           /  |   |
                          /   |   |
                         /    |   |
                        /     |   |
                       /      |   |
                      /       |   |
                     /-------------








*/

C++: #include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef tuple<int, int> duo;
const int dx[] = {0, 0, 1, -1, 1, 1, -1, -1};
const int dy[] = {1, -1, 0, 0, 1, -1, 1, -1};
const int Mod = 1000000000 + 0;
//{{{ templates
#define TT_ template<typename T>inline
#define TTF_ template<typename T,typename F>inline
TT_ T sq(T x){return x*x;}
TT_ T In(){T x;cin>>x;return x;}
TT_ void Out(T&x){cout<<x;}
TT_ void sort(T&v){sort(begin(v),end(v));}
TT_ void revs(T&v){reverse(begin(v),end(v));}
TT_ void uniq(T&v){sort(v);v.erase(unique(begin(v),end(v)),end(v));}
TT_ int ubnd(T&v,typename T::value_type x){return upper_bound(begin(v),end(v),x)-begin(v);}
TT_ int lbnd(T&v,typename T::value_type x){return lower_bound(begin(v),end(v),x)-begin(v);}
TTF_ void inpt(T&v,int n,F f){for(v.reserve(n);n--;v.emplace_back(f()));}
TTF_ void show(T&v,F f,string d=" ",string e="\n"){int i=0;for(auto&x:v)i++&&(cout<<d),f(x);cout<<e;}
TT_ typename T::iterator minel(T&v){return min_element(begin(v),end(v));}
TT_ typename T::iterator maxel(T&v){return max_element(begin(v),end(v));}

inline void fast_io(){ios_base::sync_with_stdio(0);cin.tie(0);}
inline int in(){int x;scanf("%d",&x);return x;}
inline ll pow_mod(ll a,ll k,ll m){ll r=1;for(;k>0;a=a*a%m,k>>=1)if(k&1)r=r*a%m;return r;}
inline ll mod_inv(ll a,ll p){return pow_mod(a,p-2,p);}
//}}} priority_queue queue deque front stringstream max_element min_element insert count make_tuple

double sq(double x){ return x * x; }
double sqs(double x, double y){ return sq(x) + sq(y); }

// ax + by = c
// dx + ey = f
void F(double *x, double *y, double a, double b, double c, double d, double e, double f)
{
  *y = (c * d - f * a) / (d * b - e * a);
  *x = (b * f - e * c) / (d * b - e * a);
}

int main()
{
  int n = in();
  while (n--){
    double x0, y0, x1, y1, x2, y2;
    cin >> x0 >> y0 >> x1 >> y1 >> x2 >> y2;
    // (x - a)^2 + (y - b)^2 = r^2
    // x^2 + y^2 + lx + my + n = 0
    // -a = l / 2
    // -b = m / 2
    double l, m;
    F(&l, &m, x0 - x1, y0 - y1, sqs(x1, y1) - sqs(x0, y0), x0 - x2, y0 - y2, sqs(x2, y2) - sqs(x0, y0));
    double px = -l / 2, py = -m / 2;
    double r = sqrt(sq(x0 - px) + sq(y0 - py));
    printf("%.3lf %.3lf %.3lf\n", px, py, r);
  }
  return 0;
}