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))
	}
}

Python: # -*- coding: utf-8 -*-

import cmath

class Point(object):
    def __init__(self, x, y):
        self.point = complex(x, y)
    def __str__(self):
        return "x = {0}, y = {1}".format(self.point.real, self.point.imag)

class Triangle(Point):
    def __init__(self, a, b, c):
        self.a = a
        self.b = b
        self.c = c

        self.edgeA = abs(b.point-c.point)
        self.edgeB = abs(c.point-a.point)
        self.edgeC = abs(a.point-b.point)

        self.angleA = Triangle.angle(self.edgeA, self.edgeB, self.edgeC)
        self.angleB = Triangle.angle(self.edgeB, self.edgeC, self.edgeA)
        self.angleC = Triangle.angle(self.edgeC, self.edgeA, self.edgeB)


    def angle(A, B, C):
        return cmath.acos( (B*B+C*C-A*A)/(2*B*C) )



    def circumscribedCircleRadius(self):
        return abs((self.edgeA/cmath.sin(self.angleA))/2)


    def circumscribedCircleCenter(self):
        A = cmath.sin(2*self.angleA)
        B = cmath.sin(2*self.angleB)
        C = cmath.sin(2*self.angleC)
        X = (self.a.point.real*A + self.b.point.real*B + self.c.point.real*C) / (A+B+C)
        Y = (self.a.point.imag*A + self.b.point.imag*B + self.c.point.imag*C) / (A+B+C)
        return complex(X, Y)

line = list(map(float, input().split()))
p1 = Point(line[0], line[1])
p2 = Point(line[2], line[3])
p3 = Point(line[4], line[5])
T = Triangle(p1, p2, p3)
center = T.circumscribedCircleCenter()
print("{0:.4f} {1:.4f} {2:.4f}".format(center.real, center.imag, T.circumscribedCircleRadius()))

Python: import sys
import math

if sys.version_info[0] >= 3:
    raw_input = input
N = int(raw_input())
for i in range(N):
    x1, y1, x2, y2, x3, y3 = [float(e) for e in raw_input().split()]
    a1 = 2*x2 - 2*x1
    b1 = 2*y2 - 2*y1
    c1 = x1**2 - x2**2 + y1**2 - y2**2
    a2 = 2 * x3 - 2 * y1
    b2 = 2 * y3 - 2 * y1
    c2 = x1**2 - x3**2 + y1**2 - y3**2
    x = (b1*c2-b2*c1)/(a1*b2-a2*b1)
    y = (c1*a2-c2*a1)/(a1*b2-a2*b1)
    print("%.3f %.3f %.3f" %(x, y, math.hypot(x1-x, y1-y)))

Python: import math
n = int(input())

round = lambda x:(x*1000*2+1)//2/1000

for i in range(n):
    x1,y1,x2,y2,x3,y3 = [ float(s) for s in input().split() ]
    r1 = x1*x1 + y1*y1
    r2 = x2*x2 + y2*y2
    r3 = x3*x3 + y3*y3
    x1_x2 = x1 - x2
    y1_y2 = y1 - y2
    x1_x3 = x1 - x3
    y1_y3 = y1 - y3
    r1_r2 = r1 - r2
    r1_r3 = r1 - r3
    if x1_x2 == 0:
        py = r1_r2 / (2*y1_y2)
        px = (r1_r3 - 2*y1_y3*py) / (2*x1_x3)
    else:
        py = (r1_r2 * x1_x3 - r1_r3 * x1_x2) / (2*(y1_y2 * x1_x3 - y1_y3 * x1_x2))
        px = (r1_r2 - 2*y1_y2*py) / (2*x1_x2)
    r = math.sqrt((x1-px)**2 + (y1-py)**2)
    print('{:.3f}'.format(0+px),'{:.3f}'.format(0+py),'{:.3f}'.format(0+round(r)))

Python: from math import sqrt

def circle(x1, y1, x2, y2, x3, y3):
    if x1 == 0:
        dx = 1
        x1 = x1 + dx
        x2 = x2 + dx
        x3 = x3 + dx
    else:
        dx = 0
    if y2 == 0:
        dy = 1
        y1 = y1 + dy
        y2 = y2 + dy
        y3 = y3 + dy
    else:
        dy = 0
    A = [[x1, y1, 1, 1, 0, 0],[x2, y2, 1, 0, 1, 0],[x3, y3, 1, 0, 0, 1]]
#    print(A)
    for i in range(3):
        A[0] = [x/A[0][0] for x in A[0]]
        A[1] = [A[1][j] - A[1][0] * A[0][j] for j in range(6)]
        A[2] = [A[2][j] - A[2][0] * A[0][j] for j in range(6)]
#        print(A)
        for j in range(3):
            A[j] = A[j][1:] + A[j][:1]
        A = A[1:] + A[:1]
#        print(A)
    for i in range(3):
        A[i] = A[i][:3]
#    print(A)
    V = [-x1**2-y1**2, -x2**2-y2**2, -x3**2-y3**2]
    M = [(A[i][0] * V[0] + A[i][1] * V[1] + A[i][2] * V[2]) for i in range(3)]
    xcenter = -0.5 * M[0] - dx
    ycenter = -0.5 * M[1] - dy
    radius = sqrt((M[0]**2) /4 + (M[1]**2) /4 - M[2])
    return xcenter, ycenter, radius

n = int(input())
for line in range(n):
    x1, y1, x2, y2, x3, y3 = map(float, input().split())
    xc, yc, ra = circle(x1, y1, x2, y2, x3, y3)
    print('%.3f %.3f %.3f' % (xc, yc, ra))