near (400/Pi)*li, You are right.

來源: jinjing 於 2010-05-26 15:14:20 [] [舊帖] [給我悄悄話] 閱讀數 : (126 bytes)
回答: 輪子上一點移動多少距離？ 由 guest007 於 2010-05-26 08:47:03

x=r(1-sint)
y=r(1-cost)
ds=2^.5r(1-cost)^.5dt,s=Intg(2^.5r(1-cost)^.5dt)from 0 to 2Pi= 8r, so (100/2Pi*r)*8r=(400/Pi)li.

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• Agree with your answer -AnaZhang- ♀ 給 AnaZhang 發送悄悄話 AnaZhang 的博客首頁 (148 bytes) () 05/26/2010 postreply 18:36:36

• Thanks, I did not know that word before -guest007- ♀ 給 guest007 發送悄悄話 (54 bytes) () 06/02/2010 postreply 09:14:07

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