Luogu(?) CF1C Ancient Berland Circus

题目描述：传送门
题解：luogu中的Dalao写的题解已经很好了，计算几何题。。。
ps:第一次发现三角函数是弧度制的[汗]

#include
#include
#include
using namespace std;
const double PI=acos(-1.0),eps=1e-2;
double dis[5],p,S,sinc,r,a,b,c,d;
struct dyt{
    double x,y;
}s[5];
double gcd(double x,double y) {
    if (fabs(y)return x; 
    else if (fabs(x)return y;
    else return gcd(y,fmod(x,y));
}
int main(){
    for (int i=1;i<=3;i++) scanf("%lf %lf",&s[i].x,&s[i].y);
    int k=0;
    for (int i=1;i<3;i++)
    for (int j=i+1;j<=3;j++)
    dis[++k]=sqrt((s[i].x-s[j].x)*(s[i].x-s[j].x)+(s[i].y-s[j].y)*(s[i].y-s[j].y));
    p=(dis[1]+dis[2]+dis[3])/2;
    S=sqrt(p*(p-dis[1])*(p-dis[2])*(p-dis[3]));
    sinc=2*S/(dis[1]*dis[2]); r=dis[3]/sinc/2.0;
    a=2*asin(dis[1]/(2*r))*180.0/PI; b=2*asin(dis[2]/(2*r))*180.0/PI; c=360.0-a-b;
    d=gcd(a,gcd(b,c));
    printf("%.8lf\n",r*r*sin(d*PI/180.0)*360.0/(2.0*d));
    return 0;
}