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: def main():
    import math
    while True:
        try:
            for i in range(int(input())):
                x1,y1,x2,y2,x3,y3=map(float,input().split())

                a=y1-y2
                b=y1-y3

                if a==0:
                    x=(x1+x2)/2
                    c=(x3-x1)/(y1-y3)
                    d=(-x1-x3)/2+(y1+y3)/2
                    y=c*x+d

                elif b==0:
                    x=(x1+x3)/2
                    c=(x2-x1)/(y1-y2)
                    d=(-x1-x3)/2+(y1+y3)/2
                    y=c*x+d

                else:
                    a=(x2-x1)/(y1-y2)
                    b=(-x1-x2)/2+(y1+y2)/2
                    c=(x3-x1)/(y1-y3)
                    d=(-x1-x3)/2+(y1+y3)/2

                    x=(d-b)/(a-c)
                    y=a*x+b

                r=math.sqrt((x-x1)**2+(y-y1)**2)

                print("{0:.3f} {1:.3f} {2:.3f}".format(x,y,r))
        except:
            break

Python: import math

def da(li):
    x1,y1,x2,y2,x3,y3=[float(i) for i in li]
    xp,yp=(x2-x1)/2,(y2-y1)/2
    xq,yq=(x3-x1)/2,(y3-x1)/2
    t=(xq**2+yq**2-xp*xq-yp*yq)/(xp*yq-xq*yp)
    return x1+xp-t*yp,y1+yp+t*xp
def sis(fl):
    fls=str(fl)
    if len(fls)<6:return fls+"".join(["0" for i in range(5-len(fls))])
    if int(fls[5:6])>4:
        return fls[:4]+str(int(fls[4:5])+1)
    else:
        return fls[:5]

n=int(input())
for i in range(n):
    li=input().split(" ")
    x,y=da(li)
    print(sis(x)+" "+sis(y)+" "+sis(math.sqrt(x**2+y**2)))

Python: from math import sqrt
def f(x):
    a = (x[2] - x[4]) * (x[1] - x[3]) - (x[0] - x[2]) * (x[3] - x[5])
    b = (x[0] - x[2]) * (x[4] - x[0]) - (x[5] - x[1]) * (x[1] - x[3])
    l = 0.5 * b / a
    X = 0.5 * x[2] + 0.5 * x[4] + l * (x[3] - x[5])
    Y = 0.5 * x[3] + 0.5 * x[5] + l * (x[4] - x[2])
    R = sqrt((X - x[0]) ** 2 + (Y - x[1]) ** 2)
    print("{0:.3f} {1:.3f} {2:.3f}".format(X, Y, R))
n = int(input())
a = []
for _ in range(n):
        a.append(list((map(float, input().split()))))
for i in a:
    f(i)

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: for _ in[0]*int(input()):
 a,b,c,d,e,f=map(float,input().split())
 x=((a*a+b*b)*(d-f)+(c*c+d*d)*(f-b)+(e*e+f*f)*(b-d))/2/(a*(d-f)+c*(f-b)+e*(b-d))
 y=((a*a+b*b)*(c-e)+(c*c+d*d)*(e-a)+(e*e+f*f)*(a-c))/2/(b*(c-e)+d*(e-a)+f*(a-c))
 print(f"{x:.3f} {y:.3f} {((x-a)**2+(y-b)**2)**.5:.3f}")

Python: from decimal import Decimal
import math
for _ in range(int(input())):
    x1,y1,x2,y2,x3,y3=list(map(Decimal,input().split()))
    a=x1-x3
    b=y2-y3
    c=x2-x3
    d=y1-y3
    e=y1-y2
    f=x1+x3
    g=x2+x3
    X=(b*d*e+a*b*f-c*d*g)/2/(a*b-c*d)
    try:
        Y=-(a/d)*(X-f/2)+(y1+y3)/2
    except:
        Y=-(c/b)*(X-g/2)+(y2+y3)/2
    R=math.sqrt((x1-X)**2+(y1-Y)**2)
    print(" ".join(["{:.3f}".format(i) for i in [X,Y,R]]))