Morley's Therorem（UVA11178+几何）

题意：Morley定理，求D、E、F的坐标

思路：没什么算法，就是几何的应用。注意旋转角就好了。

转载请注明出处：寻找&星空の孩子

题目链接：UVA11178

 #include<cstdio>
 #include<cmath>
 #define PI acos(-1.0)
 using namespace std;

 struct Point
 {
     double x,y;
     Point(double x=,double y=):x(x),y(y){ }
  //   Point read_point() {scanf("%lf%lf",&this.x,&this.y);}
 };
 typedef Point Vector;
 Vector operator + (Vector A,Vector B){return Vector(A.x+B.x,A.y+B.y);}
 Vector operator - (Point A,Point 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);}

 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-B.x*A.y;}

 Vector Rotate (Vector A,double rad)
 {
     //其中rad为逆时针旋转角
     return Vector(A.x*cos(rad)-A.y*sin(rad),A.x*sin(rad)+A.y*cos(rad));
 }

 Point GetLineIntersection(Point P,Vector v,Point Q,Vector w)
 {
     Vector u=P-Q;
     if(Cross(v,w))
     {
         double t=Cross(w,u)/Cross(v,w);//精度高的时候，考虑自定义分数类
         return P+v*t;
     }
 //    else
  //       return ;
 }

 Point getD(Point A,Point B,Point C)
 {
     Vector v1=C-B;
     double a1=Angle(A-B,v1);
     v1=Rotate(v1,a1/);

     Vector v2=B-C;
     double a2=Angle(A-C,v2);
     v2=Rotate(v2,-a2/);//-表示顺时针旋转;

     return GetLineIntersection(B,v1,C,v2);

 }

 Point read_point(Point &P)
 {
     scanf("%lf%lf",&P.x,&P.y);
     return P;
 }
 int main()
 {
     int T;
     Point A,B,C,D,E,F;
     scanf("%d",&T);
     while(T--)
     {
         A=read_point(A);
         B=read_point(B);
         C=read_point(C);

 //        scanf("%lf%lf%lf%lf%lf%lf",&A.x,&A.y,&B.x,&B.y,&C.x,&C.y);
 //        printf("%.6lf %.6lf %.6lf %.6lf %.6lf %.6lf\n",A.x,A.y,B.x,B.y,C.x,C.y);
         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 ;
 }