Morley's Theorem

https://vjudge.net/problem/UVA-11178
题目大意：给定一个三角形的三个顶点，求1/3角平分线的三个交点。

#include<cstdio>
#include<iostream>
#include<cmath>
#include<complex>
using namespace std;
struct Point
{
    double x,y;
    Point(double x=0,double y=0):x(x),y(y){}

};
typedef Point Vector;
Vector operator +(Vector A,Vector B) {return Vector(A.x+B.x,A.y+B.y);}
Vector operator -(Vector A,Vector B) {return Vector(A.x-B.x,A.y-B.y);}
Vector operator *(Vector A,double p) {return Vector(A.x*p,A.y*p);}
Vector operator /(Vector A,double p) {return Vector(A.x/p,A.y/p);}
bool operator <(const Point &a,const Point &b)
{
    return a.x<b.x||(a.x==b.x&&a.y<b.y);
}
const double eps=1e-10;
int dcmp(double x)
{
    if(fabs(x)<eps) return 0;
    return x<0?-1:1;
}
bool operator ==(const Point &a,const Point &b)
{
    return dcmp(a.x-b.x)==0&&dcmp(a.y-b.y)==0;
}
double dot(Vector A,Vector B) {return A.x*B.x+A.y*B.y;}
double length(Vector A) { return sqrt(dot(A,A));}
double angle(Vector A,Vector B){return acos(dot(A,B)/length(A)/length(B)) ;}

double cross(Vector A,Vector B){return A.x*B.y-A.y*B.x;}
double Area2(Point A,Point B,Point C){return cross(B-A,C-A);}
Vector rorate(Vector A,double rad)
{
    return Vector(A.x*cos(rad)-A.y*sin(rad),A.x*sin(rad)+A.y*cos(rad));
}
Vector normal(Vector A)//左转90du，单位向量
{
    double L=length(A);
    return Vector(-A.y/L,A.x/L);
}
Point getLineIntersection(Point P,Vector v,Point Q,Vector w)//两直线的交点
{
    Vector u=P-Q;
    double t=cross(w,u)/cross(v,w);
    return P+v*t;
}
double distanceToLine(Point P,Point A,Point B)//点到直线距离
{
    Vector v1=B-A,v2=P-A;
    return fabs(cross(v1,v2))/length(v1);
}
double distanceToSegment(Point p,Point A,Point B)
{
    if(A==B) return length(p-A);
    Vector v1=B-A,v2=p-A,v3=p-B;
    if(dcmp(dot(v1,v2))<0) return length(v2);
    else if(dcmp(dot(v1,v3))>0) return length(v3);
    else return fabs(cross(v1,v2))/length(v1);
}
Point getLineProjection(Point P,Point A,Point B)//p点在AB直线上的投影
{
    Vector v=B-A;
    return A+v*(dot(v,P-A)/dot(v,v));
}
bool segmentProperIntersection(Point a1,Point a2,Point b1,Point b2)
{   //两直线是否规范相交：恰好有一个公共点并且公共点不在任何一条线段的端点
    double c1=cross(a2-a1,b1-a1),c2=cross(a2-a1,b2-a1),
           c3=cross(b2-b1,a1-b1),c4=cross(b2-b1,a2-b1);
           return dcmp(c1)*dcmp(c2)<0&&dcmp(c3)*dcmp(c4)<0;
}
bool onSegment(Point p,Point a1,Point a2)//p点是否在线段上，不包括a1，a2
{
    return dcmp(cross(a1-p,a2-p))==0&&dcmp(dot(a1-p,a2-p))<0;
}
double convexPolygonArea(Point *arr,int n)//计算多边形面积
{
    double area=0.0;
    for(int i=1;i<n-1;i++)
    {
        area+=cross(arr[i]-arr[0],arr[i+1]-arr[0]);
    }
    return fabs(area/2);

}
double PolygonArea(Point *arr,int n)//计算多边形有向面积
{
    double area=0.0;
    for(int i=1;i<n-1;i++)
    {
        area+=cross(arr[i]-arr[0],arr[i+1]-arr[0]);
    }
    return area/2;

}
Point getD(Point A,Point B,Point C)
{
    Vector v1=A-B,v2=C-B;
    double a1=angle(v1,v2);
    Vector v3=B-C,v4=A-C;
    double a2=angle(v3,v4);
    Vector l1=rorate(v2,a1/3.0),l2=rorate(v3,-a2/3.0);
    return getLineIntersection(B,l1,C,l2);

}
int main()
{
   int t;
   scanf("%d",&t);
   Point A,B,C,D,E,F;
   while(t--)
   {
       scanf("%lf%lf",&A.x,&A.y);
       scanf("%lf%lf",&B.x,&B.y);
       scanf("%lf%lf",&C.x,&C.y);
       D=getD(A,B,C);
       E=getD(B,C,A);
       F=getD(C,A,B);
       printf("%.6f %.6f %.6f %.6f %.6f %.6f\n",D.x,D.y,E.x,E.y,F.x,F.y);
   }
}