uva 11178

题意：根据A,B,C三点的位置确定D,E,F三个点的位置。

贴模板

 #include<cstdio>
 #include<cmath>
 #include<cstring>
 #include<algorithm>
 #include<iostream>
 #include<memory.h>
 #include<cstdlib>
 #include<vector>
 #define clc(a,b) memset(a,b,sizeof(a))
 #define LL long long int
 using namespace std;
 const int N=;
 const int inf=0x3f3f3f3f;
 const double eps = 1e-;

 struct Point
 {
     double x, y;
     Point(double x = , double y = ) : 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 - (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);
 }

 bool operator < (const Point& a, const Point& b)
 {
     return a.x < b.x || (a.x == b.x && a.y < b.y);
 }

 int dcmp(double x)
 {
     if(fabs(x) < eps) return ;
     return x <  ? - : ;
 }

 bool operator == (const Point& a, const Point& b)
 {
     return dcmp(a.x - b.x) ==  && dcmp(a.y - b.y) == ;
 }

 double Dot(Vector A, Vector B)//点乘
 {
     return A.x * B.x + A.y * B.y;
 }

 double Length(Vector A) //向量的模
 {
     return sqrt(Dot(A, A));
 }

 double Angle(Vector A, Vector B)//两个向量的夹角
 {
     return acos(Dot(A, B) / Length(A) / Length(B));
 }

 double Cross(Vector A, Vector B)//叉乘
 {
     return A.x * B.y - A.y * B.x;
 }

 double Area(Point A, Point B, Point C)//三个点组成的三角形的面积
 {
     return Cross(B - A, C - A);
 }

 Vector Rotate(Vector A, double rad)   //向量A逆时针旋转rad弧度后的坐标
 {
     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)//求直线交点
 {
     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/);

     Vector v2 = B - C;
     double a2 = Angle(A-C, v2);
     v2 = Rotate(v2, -a2/);

     return GetLineIntersection(B, v1, C, v2);
 }
 int main()
 {
     int T;
     Point A, B, C, D, E, F;
     scanf("%d",&T);
     while(T--)
     {
         scanf("%lf%lf%lf%lf%lf%lf",&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("%lf %lf %lf %lf %lf %lf\n", D.x, D.y, E.x, E.y, F.x, F.y);
     }
     return ;
 }