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 <cstdio>
#include <cmath>
using namespace std;
#define REP0(i,n) for(int i=0;i<n;++i)
#define REP1(i,n) for(int i=1;i<=n;++i)
#define ALL(c) (c).begin(),(c).end()
const double eps=1e-9;
struct seg{double a,b,c;};
seg calc(double x1,double y1,double x2,double y2){
	double a=y1-y2,b=x2-x1,c=x2*y1-x1*y2;
	seg ret;
	ret.a=a;
	ret.b=b;
	ret.c=c;
	return ret;
}
int main(){
	int n;
	scanf("%d",&n);
	REP0(i,n){
		double x1,y1,x2,y2,x3,y3,ox,oy;
		scanf("%lf%lf%lf%lf%lf%lf",&x1,&y1,&x2,&y2,&x3,&y3);
		seg k=calc(x1,y1,x2,y2);
		seg l=calc(x1,y1,x3,y3);
		double mx1=(x1+x2)/2,my1=(y1+y2)/2,mx2=(x1+x3)/2,my2=(y1+y3)/2;
		seg s1,s2;
		s1.a=k.b;
		s1.b=-k.a;
		s1.c=s1.a*mx1+s1.b*my1;
		s2.a=l.b;
		s2.b=-l.a;
		s2.c=s2.a*mx2+s2.b*my2;
		ox=(s1.c*s2.b-s2.c*s1.b)/(s1.a*s2.b-s2.a*s1.b);
		oy=(s1.a*s2.c-s2.a*s1.c)/(s1.a*s2.b-s2.a*s1.b);
		printf("%.3lf %.3lf %.3lf\n",ox+eps,oy+eps,sqrt((x1-ox)*(x1-ox)+(y1-oy)*(y1-oy))+eps);
	}
	return 0;
}

C++: #include <iostream>
#include <algorithm>
#include <complex>
#include <vector>
#include <cmath>
using namespace std;
typedef complex<double> P;

const double eps = 1e-5;
vector<P> ps(3);
double R;

double eval(P p) {
  double sum = 0;
  for(int i = 0; i < ps.size(); ++i)
    sum += abs(R-abs(p-ps[i]));
  return sum;
}

P getBestP(P o, double r) {
  double s = 200;
  double mini = 1e100;
  P bestP;
  double begin = -r;
  double end = r;
  for(int i = 0; i < s; ++i) {
    for(int j = 0; j < s; ++j) {
      P v(begin + j/s*(end-begin), begin + i/s*(end-begin));
      P p = o+v;
      double tmp = eval(p);
      if(tmp < mini) {
	mini = tmp;
	bestP = p;
      }
    }
  }
  return bestP;
}

int main() {
  int Tc;
  cin >> Tc;
  for(int tc = 0; tc < Tc; ++tc) {
    for(int i = 0; i < ps.size(); ++i) cin >> ps[i].real() >> ps[i].imag();
    R = abs(ps[1]-ps[2])/abs(sin(arg(ps[1]-ps[0])-arg(ps[2]-ps[0])))/2.0;
    P res(0,0);
    for(double r = 100.0; r > eps; r *= 0.1) {
      res = getBestP(res, r);
    }
    printf("%.3f %.3f %.3f\n", res.real(), res.imag(), R);
  }
  return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <cmath>

void gradcut(double *a,double *b,double x1,double y1,double x2,double y2);

int main() {
    double x[3],y[3],a[2],b[2],rx,ry,r;
    int n;
    std::cin >> n;
    for(int j=0;j<n;j++){
        int am=0,add=1;;
        for(int i=0;i<3;i++) std::cin >> x[i] >> y[i];
        for(int i=0;i<3;i++){
            if(i==2) add=-2;
            if(x[i]!=x[i+add]&&y[i]!=y[i+add]){
                gradcut(&a[am],&b[am],x[i],x[i+add],y[i],y[i+add]);
                am++;
                if(am>2) break;
            }else if(x[i]==x[i+add]){
                a[am]=0;
                b[am]=(y[i]+y[i+add])/2;
                am++;
                if(am>2) break;
            }
        }


        rx = (b[1]-b[0])/(a[0]-a[1]);
        ry = a[0]*rx+b[0];
        r=sqrt((x[0]-rx)*(x[0]-rx)+(y[0]-ry)*(y[0]-ry));
        printf("%.3f %.3f %.3f\n",rx,ry,r);
    }
    return 0;
}

void gradcut(double *a,double *b,double x1,double x2,double y1,double y2){
    *a=-(x2-x1)/(y2-y1);
    *b=(y1+y2)/2-(*a)*(x1+x2)/2;
}

C++: #include <bits/stdc++.h>
using namespace std;
using uint = unsigned int;
using lint = long long int;
using ulint = unsigned long long int;
template<class T = int> using V = vector<T>;
template<class T = int> using VV = V< V<T> >;
template<class T, class U> void assign(V<T>& v, int n, const U& a) { v.assign(n, a); }
template<class T, class... Args> void assign(V<T>& v, int n, const Args&... args) { v.resize(n); for (auto&& e : v) assign(e, args...); }


using P = complex<long double>;

int main() {
  cin.tie(nullptr); ios_base::sync_with_stdio(false);
  int n; cin >> n;
  for (int _ = 0; _ < n; ++_) {
    V<P> p(3);
    for (int i = 0; i < 3; ++i) {
      long double x, y; cin >> x >> y;
      p[i] = {x, y};
    }
    P numer = 0;
    for (int i = 0; i < 3; ++i) {
      numer += p[i] * (norm(p[(i + 2) % 3]) - norm(p[(i + 1) % 3]));
    }
    P denom = 0;
    for (int i = 0; i < 3; ++i) {
      denom += p[i] * conj(p[(i + 2) % 3] - p[(i + 1) % 3]);
    }
    P r = numer / denom;
    cout << fixed << setprecision(3) << real(r) << ' ' << imag(r) << ' ' << abs(p[0] - r) << '\n';
  }
}