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++: // clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
// #define main int main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
#define stlice(from, to) substr(from, (to) - (from) + 1)
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
using namespace std;
using pii = pair<int, int>;
using vi = vector<int>;
using vd = vector<double>;
using vc = vector<char>;
using vb = vector<bool>;
using vs = vector<string>;
using vpii = vector<pii>;
using vvi = vector<vi>;
using vvb = vector<vb>;
using vvpii = vector<vpii>;
template<typename A> using fn = function<A>;
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = acos(-1);
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
constexpr bool odd(const int &n) { return n & 1; }
constexpr bool even(const int &n) { return !odd(n); }
template<typename V> constexpr typename V::value_type sum(const V &v) { return accumulate(all(v), 0); }
void solve();
main { solve(); return 0; }
// clang-format on

double floorp(double x, int prec) {
  double t = pow(10, prec);
  return double((int) (x * t)) / t;
}

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

template<typename T>
constexpr T det2(const T &a1, const T &a2, const T &b1, const T &b2) {
  return a1 * b2 - b1 * a2;
}

void solve() {
  int n;
  cin >> n;
  rep(i, n) {
    double x1, y1, x2, y2, x3, y3;
    cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;
    double npx = det2(y2 - y1, y3 - y1, f(x1) - f(x2) + f(y1) - f(y2), f(x1) - f(x3) + f(y1) - f(y3));
    double npy = det2(y2 - y1, y3 - y1, f(x1) - f(x2) + f(y1) - f(y2), f(x1) - f(x3) + f(y1) - f(y3));
    double dp  = 2 * det2(x2 - x1, x3 - x1, y2 - y1, y3 - y1);
    double px = npx / dp, py = npy / dp;
    double r = sqrt(f(px - x1) + f(py - y1));
    cout << prec(3) << floorp(px, 3) << ' ' << floorp(py, 3) << ' ' << floorp(r, 3) << endl;
  }
}

C++: #include <iostream>
#include <stdlib.h>
#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;
        cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3;

        double a1 = 2 * (x2 - x1), a2 = 2 * (x3 - x1),
               b1 = 2 * (y2 - y1), b2 = 2 * (y3 - y1),
               c1 = x1 * x1 - x2 * x2 + y1 * y1 - y2 * y2,
               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),
               r = sqrt(pow(x1 - px, 2) + pow(y1 - py, 2));
        printf("%.3f %.3f %.3f\n", px, py, r);
    }
    return 0;
}

C++: #include <cmath>
#include <iostream>
using namespace std;
int n; double ax, ay, bx, by, cx, cy;
int main() {
	cin >> n;
	while (n--) {
		cin >> ax >> ay >> bx >> by >> cx >> cy;
		double a1 = 2 * (bx - ax);
		double b1 = 2 * (by - ay);
		double c1 = ax * ax - bx * bx + ay * ay - by * by;
		double a2 = 2 * (cx - ax);
		double b2 = 2 * (cy - ay);
		double c2 = ax * ax - cx * cx + ay * ay - cy * cy;
		double x = (b1 * c2 - b2 * c1) / (a1 * b2 - a2 * b1);
		double y = (c1 * a2 - c2 * a1) / (a1 * b2 - a2 * b1);
		double r = hypot(ax - x, ay - y);
		printf("%.3f %.3f %.3f\n", x, y, r);
	}
	return 0;
}

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

int main(){
	int num;
	cin>>num;
	for(int i=0;i<n;i++){
		double a,b,c,d,e,f;
		double x1,y1,x2,y2,x3,y3;
		cin>>x1>>y1>>x2>>y2>>x3>>y3;
	
		a=x1-x2;
		b=y1-y2;
		c=x2-x3;
		d=y2-y3;
		e=(x2*x2+y2*y2)-(x1*x1+y1*y1);
		f=(x3*x3+y3*y3)-(x2*x2+y2*y2);
		double l=(e*d-f*b)/(a*d-c*b);
		double m=(c*e-a*f)/(c*b-a*d);
		double n=-1*x1*x1-(y1*y1)-l*x1-m*y1;
	
		double x=-1*l/2.0;
		double y=-1*m/2.0;
		double r=sqrt(l*l+m*m-4*n)/2.0;
		printf("%.3f %.3f %3f\n",x,y,r);
	}
}