不好意思老做网友出的题，今天也来一道！

As shown, ABCD is a rectangle. BF is the distance of point B to line AE. 
 

1) how much is the maximum of BF? List all the conditions that result in this maximum.

2) under the same conditions as above, verify A is midpoint of EF.

 

 

 

所有跟帖： 

• 要求的是距离BF的最大值，那什么在变化？ -贫论贫论- ♂ (137 bytes) () 05/08/2026 postreply 04:39:42

• 理解完全正确。矩形的形状可变，面积是常数。 -askerfor- ♂ (0 bytes) () 05/08/2026 postreply 05:04:01

• sABE能算出来，所以AE最小就行。如果AB=x, AE^2 = (270/x)^2+(x/2)^2 -got66- ♂ (0 bytes) () 05/08/2026 postreply 05:57:29

• 思路清晰，但没有做完 -askerfor- ♂ (70 bytes) () 05/08/2026 postreply 07:42:50

• 奇怪 -got66- ♂ (197 bytes) () 05/08/2026 postreply 08:08:44

• 摆迷魂阵：））） -askerfor- ♂ (225 bytes) () 05/08/2026 postreply 08:41:47