I guess this is correct.

來源: 亂彈 於 2009-03-04 17:50:00 [] [博客] [舊帖] [給我悄悄話] 閱讀數 : (200 bytes)
本帖於 2009-03-18 18:55:04 時間, 由普通用戶 康MM 編輯
回答: 2005全國高中數學聯賽 -- 正方形剖分 由 於德利 於 2009-03-01 05:07:09

Basically using Euler's formula, V-E+F=1, where F=2005.
Besides the four corners, every vertex is of degree at least 3, so we have 8+3(V-4) ≤ 2E. Combine these two, we get the answer.

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