Uva11178计算几何

题目链接：点击打开链接

题意：做三角形ABC内角的三等分线，交与DEF点求这三点的坐标

D点是向量BC向逆时针旋转B/3弧度和向量CB顺时针旋转C/3的交点，其他也是也一样，用向量旋转和直线相交的模板就可以做出来了

#include <iostream>
#include<cstdio>
#include<cmath>
using namespace std;

const double eps = 1e-8;



struct Point//点 向量
{
    double x,y;
    Point(double x=0,double y=0):x(x),y(y) {}
};
typedef  Point  Vector;
//向量使用点作为表示方法 结构相同 为了代码清晰定义宏加以区别
int dcmp(double x) //三态函数 处理与double零有关的精度问题
{
    if(fabs(x) < eps)    return 0;
    return x<0 ? -1 : 1;
}
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 Vector& A, const Vector& B)
{
    return dcmp(A.x-B.x)==0 && dcmp(A.y-B.y)==0;
}
bool operator < (const Point&a,const Point &b)
{
    return a.x<b.x||(a.x==b.x&&a.y<b.y);
}

double Dot(Vector A, Vector B) //向量点积
{
    return A.x * B.x + A.y * B.y;
}
double Cross(Vector A, Vector B)  //向量叉积
{
    return A.x * B.y - A.y * B.x;
}
double Length(Vector A) //向量长度
{
    return sqrt(Dot(A,A));
}
double Angle(Vector A, Vector B)  //向量夹角
{
    return acos(Dot(A,B) / Length(A) / Length(B));
}
Vector Rotate(Vector A, double rad) //向量旋转 rad为弧度
{
    return Vector(A.x * cos(rad) - A.y * sin(rad), A.x * sin(rad) + A.y * cos(rad));
}
//直线向量参数方程 P+tv P为点,v为单位向量 (v长度无用)
Point GetLineIntersection(Point P, Vector v, Point Q, Vector w)//获取直线交点
{
    //调用应保证P,Q有交点 : 即 Cross(v,w)!=0
    Vector u = P-Q;
    double t = Cross(w,u) / Cross(v,w);
    return P+v*t;
}

Point getD(Point A,Point B,Point C)
{
    Vector v1=C-B;
    double a1=Angle(A-B,v1);
    v1=Rotate(v1,a1/3);
    Vector v2=B-C;
    double a2=Angle(A-C,v2);
    v2=Rotate(v2,-a2/3);
    return GetLineIntersection(B,v1,C,v2);
}
Point read_point()
{
    double x,y;
    scanf("%lf %lf",&x,&y);
    return Point(x,y);
}
 main()
{
   int T;
   Point A,B,C,D,E,F;
   scanf("%d",&T);
   while(T--)
   {
       A=read_point();
       B=read_point();
       C=read_point();
       D=getD(A,B,C);
       E=getD(B,C,A);
       F=getD(C,A,B);
       printf("%.6lf %.6lf %.6lf %.6lf %.6lf %.6lf\n",D.x,D.y,E.x,E.y,F.x,F.y);
   }
    return 0;
}