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※ 引述《darkseer (公假中)》之銘言: : ※ 引述《chaogold (新扇不扇不擅訕新)》之銘言: : : 每一次操作的正n邊形是同一個? : : 鏡射出來的正n邊形是一直在的嗎? : 我的表達實在不好XD : 直接po原文好了 : Let P be an n-gon , lying on a plane. We name its edges 1,2,3,..........n. : If S = s_1, s_2,.............. be a finite or infinite sequence such that for each i s_i is in {1,2........n}. : We move P in accordance with the sequence S such that we first reflect P through s_1 : ( the number s_i corresponds to the s_i th edge of the polygon P ) and then through s_2 : and so on. Show the following holds : : a) Show that there exists a infinite sequence S such that if we move P according to S then : then we can cover the whole plane. : b) Prove that the sequence S is'nt periodic. : c) Assume that P is a regular pentagon with the radius of its circumcircle as 1 and let D be : another circle with radius 1.00001 lying in the plane arbitrary. Does there exist a sequence : S such that we move P accordingly then P reside in D completely. : 原題中的(a)就是我問的 : (b)(c)簡單的多(好奇怪的配置XD) 歐歐我懂意思了, 你表達的很清楚是我剛好不太了解 ~XD 十分有趣的問題 讓我想到另一個印度人問過的問題 我PO在這一篇後面好了 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 61.226.0.176