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Re:弱弱的问一句， 知道A, B的坐标怎么求出C, D的坐标哇~~

Posted by rayafjyblue at 2011-05-19 22:02:41 on Problem 2002
In Reply To:弱弱的问一句， 知道A, B的坐标怎么求出C, D的坐标哇~~ Posted by:c__ at 2011-03-09 22:09:29 
如果A(x1, y1), B(x2, y2) ,则C(x3, y3),D(x4, y4) 为：
       x3=x1+(y1-y2);y3=y1-(x1-x2);   (在直线AB上方)
       x4=x2+(y1-y2);y4=y2-(x1-x2)
或：    x3=x1-(y1-y2);y3=y1+(x1-x2);   (在直线AB下方)
       x4=x2-(y1-y2);y4=y2+(x1-x2)
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