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: 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); p = x1**2 - x2**2 + y1**2 - y2**2
    c = 2*(x1 - x3); d = 2*(y1 - y3); q = x1**2 - x3**2 + y1**2 - y3**2
    det = a*d - b*c
    x = d*p - b*q; y = a*q - c*p
    if det < 0:
        x = -x; y = -y; det = -det
    x /= det; y /= det
    r = ((x - x1)**2 + (y - y1)**2)**.5
    print("%.03f %.03f %.03f" % (x, y, r))

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

import sys

def length(a, b):
    return ((a[0] - b[0])**2 + (a[1] - b[1])**2)**0.5

def solve_sim_equ(a, b, c, d, e, f):
    '''
    From Problem 0004.
    This function solves following equation.
    ax + by = c
    dx + ey = f
    '''
    if a==0 and d==0:
        if b==0 and e==0:
            return 0., 0.
        if b != 0:
            return 0., c/b+0.
        else:
            return 0., f/e+0.
    elif b==0 and e==0:
        if a != 0:
            return 0., d/a+0.
        else:
            return 0., a/d+0.

    if b == 0:
        a, d = d, a
        b, e = e, b
        c, f = f, c
    g = e / b
    x = (g*c - f) / (g*a - d)
    y = (c - a*x) / b
    return x+0., y+0.


def circumscribed_circle(x, y, z):
    def get_equ_coef(p, q):
        h_x = (p[0] + q[0]) / 2
        h_y = (p[1] + q[1]) / 2
        a = q[1] - p[1]
        b = p[0] - q[0]
        c = b * h_x - a * h_y
        return b, -a, c
    coef = get_equ_coef(x, y) + get_equ_coef(y, z)
    center = solve_sim_equ(*coef)
    r = length(center, x)
    return center, r


def main():
    N = int(input())
    for i in range(N):
        vs = [float(v) for v in input().split()]
        a = (vs[0], vs[1])
        b = (vs[2], vs[3])
        c = (vs[4], vs[5])
        center, r = circumscribed_circle2(a, b, c)
        print('{0:.3f} {1:.3f} {2:.3f}'.format(center[0], center[1], r))


if __name__ == '__main__':
    main()

Python: n = int(input())
datasets = [0]*n
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))

Python: for _ in[0]*int(input()):
 a,d,b,e,c,f=map(float,input().split())
 z=2*(b*f-c*e+c*d-a*f+a*e-b*d)
 x=((e-f)*(a**2+d**2)+(f-d)*(b**2+e**2)+(d-e)*(c**2+f**2))/z
 y=((c-b)*(a**2+d**2)+(a-c)*(b**2+e**2)+(b-a)*(c**2+f**2))/z
 print('{0:.3f} {1:.3f} {2:.3f}'.format(x,y,((a-x)**2+(d-y)**2)**0.5))