Go: package main

import (
	"fmt"
	"math"
)

func main() {
	n := scanInt()
	for i := 0; i < n; i++ {
		cal()
	}
}

func scanInt() int {
	var n int
	fmt.Scanf("%d", &n)
	return n
}

func cal() {
	var x1, y1, x2, y2, x3, y3 float64
	fmt.Scanf("%f%f%f%f%f%f", &x1, &y1, &x2, &y2, &x3, &y3)
	a := 2 * (x1 - x2)
	b := 2 * (y1 - y2)
	c := 2 * (x1 - x3)
	d := 2 * (y1 - y3)
	e := x1*x1 - x2*x2 + y1*y1 - y2*y2
	f := x1*x1 - x3*x3 + y1*y1 - y3*y3

	px := (d*e - b*f) / (a*d - b*c)
	py := (a*f - c*e) / (a*d - b*c)

	r := math.Sqrt((x1-px)*(x1-px) + (y1-py)*(y1-py))
	fmt.Printf("%.3f %.3f %.3f\n", px, py, r)
}

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
        # ３辺の長さ
        self.edgeA = abs(b.point-c.point)
        self.edgeB = abs(c.point-a.point)
        self.edgeC = abs(a.point-b.point)
        # ３角の大きさ
        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)

    # 角度を求める
    def angle(A, B, C):
        return cmath.acos( (B*B+C*C-A*A)/(2*B*C) )


    # 外接円の半径
    def circumscribedCircleRadius(self):
        return abs((self.edgeA/cmath.sin(self.angleA))/2)

    # 外心
    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 math

def Cramer(c):
	den = c[0]*c[4] - c[1]*c[3]
	return [(c[2]*c[4] - c[1]*c[5]) / den, (c[0]*c[5] - c[2]*c[3]) / den]

n = eval(input())
for i in range(n):
	c = [eval(item) for item in input().split()]
	sol = Cramer([2*(c[0] - c[2]),\
				  2*(c[1] - c[3]),\
				  c[0]**2 + c[1]**2 - c[2]**2 - c[3]**2,\
				  2*(c[0] - c[4]),\
				  2*(c[1] - c[5]),\
				  c[0]**2 + c[1]**2 - c[4]**2 - c[5]**2])
	r = math.sqrt((sol[0] - c[0])**2+(sol[1] - c[1])**2)
	print('%.3f %.3f %.3f' %(sol[0], sol[1], r))

Python: from math import sqrt
n=int(input())
for i in range(n):
	x1,y1,x2,y2,x3,y3=map(int,input().split())
	x4=((y1-y3)*(y1**2-y2**2+x1**2-x2**2)-(y1-y2)*(y1**2-y3**2+x1**2-x3**2))/(2*(y1-y3)*(x1-x2)-2*(y1-y2)*(x1-x3))
	y4=((x1-x3)*(x1**2-x2**2+y1**2-x1**2)-(x1-x2)*(x1**2-x3**2+y1**2-y3**2))/(2*(x1-x3)*(y1-y2)-2*(x1-x2)*(y1-y3))
	r=sqrt((x1-x4)**2+(y1-y4)**2);
	print("{:.3f} {:.3f} {:.3f}".format(x4,y4,r))

Python: #!/usr/bin/env python
from math import *
def g(x):
	y = (int((1000 * abs(x)) * 2 + 1) // 2) / 1000
	if x < 0:
		y *= -1
	return y
def func(x):
	x1, y1, x2, y2, x3, y3 = x

	vx1 = x2 - x1
	vy1 = y2 - y1
	vx2 = x3 - x1
	vy2 = y3 - y1
	k = (vx2 ** 2 + vy2 ** 2 - vx1 * vx2 - vy1 * vy2) / (vy1 * vx2 - vx1 * vy2) / 2
	x = vx1 / 2 + k * vy1 + x1
	y = vy1 / 2 - k * vx1 + y1
	r = sqrt((x1 - x) * (x1 - x) + (y1 - y) * (y1 - y))
	x = "{0:.3f}".format(g(x))
	y = "{0:.3f}".format(g(y))
	r = "{0:.3f}".format(g(r))
	print(x + " " + y + " " + r)
n = int(input())
a = []
for _ in range(n):
	a.append(list((map(float, input().split()))))
for i in a:
	func(i)

Python: import math
a=int(input())
for i in range(a):
    x1,y1,x2,y2,x3,y3=[float(j) for j in input().split()]
    A=x1**2+y1**2-x2**2-y2**2
    B=x2**2+y2**2-x3**2-y3**2
    x12=x1-x2
    x23=x2-x3
    y12=y1-y2
    y23=y2-y3
    x=(y23*A-y12*B)/(2*(x12*y23-x23*y12))
    if (y12==0):
        y=(B-2*x23*x)/(2*y23)
    else:
        y=(A-2*x12*x)/(2*y12)
    r=math.sqrt((x1-x)**2+(y1-y)**2)
    print('{:.3f} {:.3f} {:.3f}'.format(x,y,r))

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

for i in range(n):
    l = input()
    x1,y1,x2,y2,x3,y3=map(float,l.split(' '))
    a_2 = (x1 - x2)**2 + (y1 - y2)**2
    b_2 = (x2 - x3)**2 + (y2 - y3)**2
    c_2 = (x3 - x1)**2 + (y3 - y1)**2
    cos_a_2 = (b_2 + c_2 - a_2)**2/(4* b_2 * c_2)
    sin_a_2 = 1 - cos_a_2
    r = round(sqrt(a_2/sin_a_2)/2,3)
    a = (x1**2 - x3**2 + y1**2 - y3**2)*(x2 - x1)
    b = (x1**2 - x2**2 + y1**2 - y2**2)*(x3 - x1)
    c = (y2 - y1)*(x3 - x1)
    d = (y3 - y1)*(x2 - x1)
    py = round((a-b)/(c-d)/2,3)
    a = (x1**2 - x3**2 + y1**2 - y3**2)*(y2 - y1)
    b = (x1**2 - x2**2 + y1**2 - y2**2)*(y3 - y1)
    c = (x2 - x1)*(y3 - y1)
    d = (x3 - x1)*(y2 - y1)
    px = round((a-b)/(c-d)/2,3)
    print('%.3f %.3f %.3f' %(px, py, r))

Python: import math
for _ in range(int(input())):
  x1,y1,x2,y2,x3,y3=map(float,input().split())
  a,b,c=2*(x2-x1),2*(y2-y1),x1**2-x2**2+y1**2-y2**2
  aa,bb,cc=2*(x3-x1),2*(y3-y1),x1**2-x3**2+y1**2-y3**2
  x,y=(b*cc-bb*c)/(a*bb-aa*b),(c*aa-cc*a)/(a*bb-aa*b)
  print('%.3f %.3f %.3f'%(x,y,math.hypot(x1-x,y1-y)))

Python: import math

n = int(input())
positions = []
for i in range(n):
  positions.append(list(map(float, input().split())))

for i in range(n):
  ra = [positions[i][0],positions[i][1]]
  rb = [positions[i][2],positions[i][3]]
  rc = [positions[i][4],positions[i][5]]

  A = (rb[0]-rc[0])**2+(rb[1]-rc[1])**2
  B = (rc[0]-ra[0])**2+(rc[1]-ra[1])**2
  C = (ra[0]-rb[0])**2+(ra[1]-rb[1])**2

  P = A * (B+C-A)
  Q = B * (C+A-B)
  R = C * (A+B-C)

  rcc_x = (P*ra[0] + Q*rb[0] + R*rc[0]) / (P+Q+R)
  rcc_y = (P*ra[1] + Q*rb[1] + R*rc[1]) / (P+Q+R)

  radius = math.sqrt((rcc_x-positions[i][0])**2+(rcc_y-positions[i][1])**2)
  print("{0:.3f} {1:.3f} {2:.3f}".format(rcc_x,rcc_y,radius))

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
        # ３辺の長さ
        self.edgeA = abs(b.point-c.point)
        self.edgeB = abs(c.point-a.point)
        self.edgeC = abs(a.point-b.point)
        # ３角の大きさ
        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)

    # 角度を求める
    def angle(A, B, C):
        return cmath.acos( (B*B+C*C-A*A)/(2*B*C) )


    # 外接円の半径
    def circumscribedCircleRadius(self):
        return abs((self.edgeA/cmath.sin(self.angleA))/2)

    # 外心
    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()))