from math import *
p =[list(map(float,input().split())) for i in range(3)]
a,b,c=[hypot(x1-x2,y1-y2) for (x1,y1),(x2,y2) in [(p[0],p[1]),(p[0],p[2]),(p[1],p[2])]]
A,B,C=[acos((y*y+z*z-x*x)/2/z/y) for x,y,z in [(a,b,c),(b,c,a),(c,a,b)]]
R=a/2/sin(A)
def g(x,y):return x if y<1e-3 else g(y,fmod(x,y))
u=2*g(A,g(B,C))
print(round(R * R * pi / u * sin(u),7))
#include<cstdio>
#include<cmath>
#include<cstdlib>
#define PI 3.141592654
double point[3][2],ql[3],cosa[3],qsina[3],qr,s;
unsigned i,a[3],res,g,b[3]={0},c[3],d,mind;
int main()
{
for(i=0;i<3;i++)
scanf("%lf%lf",&point[i][0],&point[i][1]);
for(i=0;i<3;i++)
ql[i]=(point[i][0]-point[(i+1)%3][0])*(point[i][0]-point[(i+1)%3][0])+(point[i][1]-point[(i+1)%3][1])*(point[i][1]-point[(i+1)%3][1]);
for(i=0;i<3;i++)
{
cosa[i]=(ql[(i+2)%3]+ql[(i+1)%3]-ql[i])/(2*sqrt(ql[(i+1)%3])*sqrt(ql[(i+2)%3]));
qsina[i]=1-cosa[i]*cosa[i];
a[i]=acos(cosa[i])*1e5;
}
qr=(ql[0]/qsina[0]+ql[1]/qsina[1]+ql[2]/qsina[2])/12;
b[0]=b[1]=b[2]=1;
mind=~0;
do
{
c[0]=a[0]/b[0];
c[1]=a[1]/b[1];
c[2]=a[2]/b[2];
d=abs(c[0]-c[1])+abs(c[1]-c[2])+abs(c[2]-c[0]);
if(mind>d)
{
mind=d;
res=b[0]+b[1]+b[2];
}
i=0;
if(a[0]/b[0]<a[1]/b[1])
i=1;
if(a[i]/b[i]<a[2]/b[2])
i=2;
++b[i];
}while(b[0]+b[1]+b[2]<=100);
s=qr*sin(2*PI/res)*res/2;
printf("%.8lf\n",s);
return 0;
}
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