✔ 最佳答案
圖片參考：
http://imgcld.yimg.com/8/n/HA04628698/o/701104300138913873432490.jpg
a)
ad // bc
△a f d and △a b d with the same base ad and their height are the same.
So the area of them are the same
△a f d = △a b d
△a e d + △a b e = △a e d + △e f d
△a b e = △e f d
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New Farm A = Farm A + △abe - △efd = Farm A
New Farm B = Farm B + △efd - △abe = Farm B
So New Farm A = New Farm B
That means b d is a bisection line of the whole farm.
b)
Step 1 : Drawing the line ad .
Step 2 : Drawing the line bc passing through the point f such that bc // ad ,
Step 3 : Join bd , then bd is the required new boundary.
