uva10250

向量旋转

给你正方形以对角线坐标求另外对角线坐标

计算要仔细

#include<stdio.h>void main(){double x1,y1,x2,y2,x3,y3,x4,y4,cx,cy; while(scanf("%lf%lf%lf%lf",&x1,&y1,&x2,&y2)!=EOF) {if(x1==x2 && y1==y2)  printf("Impossible.\n");  else    {cx=(x1+x2)/2;cy=(y1+y2)/2;             x1-=cx;x2-=cx;y1-=cy;y2-=cy;         x3=-y1;y3=x1;x4=-x3;y4=-y3;             printf("%lf %lf %lf %lf\n",x3+cx,y3+cy,x4+cx,y4+cy);    } }}