回複：有沒有好辦法？

來源: idiot94 於 2009-03-07 10:49:37 [] [博客] [舊帖] [給我悄悄話] 閱讀數 : (409 bytes)

note each sides lengths as:
x+y=130,
x+b=90
b+a=70
a+y=110. This group of equations are from the inner circle. However the last one is redundent.

Then connect the inner circle's center with the vertices, use the condition of the outer circle, you get this equation; xa=yb. (due to the fact that the opposite angles are compliment to each other).

Solve the equations you get y-x=13.

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• 回複：回複：有沒有好辦法？ -cma- ♂ 給 cma 發送悄悄話 (14 bytes) () 03/09/2009 postreply 08:40:19

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