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: 
import sys
import math


def solv(x1, y1, x2, y2, x3, y3):
    if y2 == y1:
        xp = 0.5 * (x1 + x2)
        yp = (x3 - x1)/(y3 - y1) * xp + 0.5 * (y1 + y3 - (x3**2 - x1**2)/(y3 - y1))
    elif y3 == y1:
        xp = 0.5 * (x1 + x3)
        yp = (x2 - x1)/(y2 - y1) * xp + 0.5 * (y1 + y2 - (x2**2 - x1**2)/(y2 - y1))
    elif y3 == y2:
        xp = 0.5 * (x2 + x3)
        yp = (x2 - x2)/(y1 - y2) * xp + 0.5 * (y2 + y1 - (x1**2 - x2**2)/(y1 - y2))
    else:
        xp = 0.5 * (y3 - y2 - (x3**2 - x1**2)/(y3 - y1) + (x2**2 - x1**2)/(y2 - y1))/((x2 - x1)/(y2 - y1) - (x3 - x1)/(y3 - y1))
        yp = (x2 - x1)/(y2 - y1) * xp + 0.5 * (y1 + y2 - (x2**2 - x1**2)/(y2 - y1))
    r = math.sqrt((x1 - xp)**2 + (y1 - yp)**2)
    return (xp, yp, r)



#input_file = open(sys.argv[1], "r")
#lines = input_file.readlines()
lines = sys.stdin.readlines()
lines.pop(0)

for line in lines:
    l = map(float, line.split(' '))
    x1 = l[0]
    y1 = l[1]
    x2 = l[2]
    y2 = l[3]
    x3 = l[4]
    y3 = l[5]
    xp, yp, r = solv(x1, y1, x2, y2, x3, y3)
    print("%5.3f %5.3f %5.3f" % (round(xp, 3), round(yp, 3), round(r, 3)))

Python: import math

n=int(input())
for i in range(n):
    deta=[float(i) for i in input().split()]
    h1=math.sqrt((deta[2]-deta[0])**2+(deta[3]-deta[1])**2)
    h2=math.sqrt((deta[4]-deta[2])**2+(deta[5]-deta[3])**2)
    h3=math.sqrt((deta[0]-deta[4])**2+(deta[1]-deta[5])**2)
    sub=(h1+h2+h3)/2
    s=math.sqrt(sub*(sub-h1)*(sub-h2)*(sub-h3))
    sum=((h1*h2*h3)/s)/4
    a=2*deta[2]-2*deta[0]
    b=2*deta[3]-2*deta[1]
    c=-(deta[0]**2+deta[1]**2-(deta[2]**2)-(deta[3]**2))
    d=2*deta[4]-2*deta[2]
    e=2*deta[5]-2*deta[3]
    f=-(deta[2]**2+deta[3]**2-(deta[4]**2)-(deta[5]**2))
    
    x=(e*c-b*f)/(a*e-b*d)
    y=(a*f-c*d)/(a*e-b*d)
    print("{0:.3f} {1:.3f} {2:.3f}".format(x,y,sum))

Python: from math import sqrt
n=int(input())
out=[]
for i in range(n):
	I=list(map(float,input().split(" ")))
	#( (x_0,y_0), (x_1,y_1) , (x_2,y_2) )
	a_1=I[2]-I[0] #x_1-x_0
	a_2=I[4]-I[0] #x_2-x_0
	b_1=I[3]-I[1] #y_1-y_0
	b_2=I[5]-I[1] #y_2-y_0
	#print(a_1,b_1,a_2,b_2)

	K=(a_2**2 -a_2*b_2+a_1**2-a_1*b_1)/(a_2*b_1-a_1*b_2)

	O_x=0.5*(b_1-K*b_2)
	O_y=0.5*(b_2+K*b_1)
	O_R=sqrt( (I[0]-O_x)**2  + (I[1]-O_y)**2 )

	out.append( '{:.3f} {:.3f} {:.3f}'.format(O_x,O_y,O_R) )



for i in out:
	print(i)

Python: from decimal import Decimal, ROUND_HALF_UP
n=int(input())
for i in range(n):
    x1,y1,x2,y2,x3,y3=map(float,input().split())
    a=2*(x1-x2)
    b=2*(y1-y2)
    c=x1**2+y1**2-x2**2-y2**2
    d=2*(x1-x3)
    e=2*(y1-y3)
    f=x1**2+y1**2-x3**2-y3**2
    x=(c*e-b*f)/(a*e-b*d)+0.0
    y=(c*d-a*f)/(b*d-a*e)+0.0
    r=((x-x1)**2+(y-y1)**2)**0.5
    print(Decimal(str(x)).quantize(Decimal('0.001'), rounding=ROUND_HALF_UP),Decimal(str(y)).quantize(Decimal('0.001'), rounding=ROUND_HALF_UP),Decimal(str(r)).quantize(Decimal('0.001'), rounding=ROUND_HALF_UP))

Python: n = int(input())
datasets = [0]*n
#datasets[k] == [x1k,y1k,x2k,y2k,x3k,y3k]
for i in range(0,n):
  datasets[i] = list(map(float,input().split()))



for data in datasets:
  x1p2=(data[0]+data[2])
  x1m2=(data[0]-data[2])
  x1p3=(data[0]+data[4])
  x1m3=(data[0]-data[4])
  y1p2=(data[1]+data[3])
  y1m2=(data[1]-data[3])
  y1p3=(data[1]+data[5])
  y1m3=(data[1]-data[5])
  x=(x1p2*x1m2*y1m3+y1p2*y1m2*y1m3-x1p3*x1m3*y1m2-y1p3*y1m3*y1m2)/(2*(x1m2*y1m3-x1m3*y1m2))
  y=(y1p2*y1m2*x1m3+x1p2*x1m2*x1m3-y1p3*y1m3*x1m2-x1p3*x1m3*x1m2)/(2*(y1m2*x1m3-y1m3*x1m2))
  r=((x-data[0])**2+(y-data[1])**2)**(1/2)
  print("{0:.3f} {1:.3f} {2:.3f}\n".format(x,y,r))