全國中小學科展

數學

格子點上的三角形

格子點上的三角形表示這個三角形三頂點的座標皆是整數。本研究先探討用平面格子點可以連出哪些三角形的相似形,再推廣到可以連出哪些多邊形的相似形;接著再研究空間中的格子點可以連出哪些三角形及多邊形的相似形,並用研究的結果討論空間中的格子點可以連出哪些正多面體。推廣到四次空間的格子點時,運用一條數論中的恆等式,發現可以做出來的三角形種類(所有相似形為同一種)居然與空間中的格子點一樣,這是個非常神奇的結果。另外,運用四平方和定理可導出,在五維空間中就能夠將所有可能用格子點連出的三角形種類連出來,這也是另一項收穫。When a triangle is formed with grid points, this means the coordinates of the vertices are all integers. This research aims to find out what type of triangles can develop into symmetries with vertices that fall right on 3 grid points on a plane. The same process is further applied to polygons. Based on the results obtained, the researcher moves on to explore what type of triangles can develop into symmetries that can be formed with spatial grid points. By using an equation in number theory to expand the study to a 4-dimension space, it is formed that the kinds of triangles—their symmetries included—which can be formed with 4-dimension grid points can also be formed in a 3-dimension space. In addition, all the possible kinds of triangles which can be formed in a 6-dimension space or up can also be formed in a 5-dimension space.

正多邊形三角剖分的探討

給定正n邊形,於內部區域新增對角線,使得對角線不交叉且內部區域皆為三角形,則將此圖形稱為正n邊形的一個『三角剖分』。考慮正n邊形的所有三角剖分,已知其數量為卡特蘭數Catalan(n-2)。在所有三角剖分的情形中,考慮旋轉與翻轉,將同構的情形視為相同,則將所有不同構的三角剖分總數記為Dn。本文對於正n邊形的不同構三角剖分進行研究,以三種面向進行探討,首先我們以不同構三角剖分的對稱性分類,發現其和化學式CnHn+2的同分異構物有相關性;再者,以相鄰三角形的最大數量進行分類,當相鄰三角形的最大數量為n-2、n-3、n-4與n-5時,得出不同構三角剖分的計算通式;最後,以三個相鄰頂點組成的外圍三角形進行分類,將『恰包含兩個外圍三角形的不同構三角剖分』、『圖論中的毛毛蟲圖(Caterpillar)』以及『化學結構相關的Losanitsch’s triangle』進行深入探討。

初等代數鏡頭下的Fibonacci Sequence

壹、研究目的:培養建構式思考方式,提高解決問題的能力。 貳、研究過程:一先查數學辭典,確定F.S.之定義。二以文字敘述替代數字敘述F.S.,並分析歸納規律性。三將發表過的有關關係式,挑選適合以代數分析研究者,研究採逆命題角度處理,共有下列七種關係式採論之。 壹、Motivation and Purpose In this study, we expect to know something about Fibonacci Sequence (F.S.) that we can understand and enjoy as a high school student. 貳、Procedure 一.Make sure the definition of F.S. 二.Use algebra instead of numerical to state F.S. 三.Select the related formulas and discuss by fundamental algebra. We get 7 types as follows

總站該設在哪裡?—另類費馬點的研究

The definition of "Fermat Point" is that a dot, which lies in a triangle, has the minimum distance to the three apexes. In other words, "Fermat Point" has the minimum distance to three dots which are not on the same line. In the broad sense, then, in a N polygon, a dot which has the minimum distance to the N apexes could be named "Fermat Point." But what if we link up the N apexes and find out that they cannot make a convex polygon? The above is what we wish to fully discuss. Our inspiration comes from a paper on"Fermat Point." It just describes N convex polygon, so we think of putting the case to naturally polygon. The case may be that it is a concave polygon or part of the apexes which lies on the same line. We would not base our study on the conventional methods. Moreover, strictly defined, the repeated line segment will not be taken into account. That is, if the "Fermat Point" drops on the line with more than two dots on it, we just count the\r line segments except for the shorter line segments which were originally included in other studies. According to the theorem, our conclusions are as follows: 1. If N points lie on the same line segment, then the "Fermat Point"can be any point on the line segment. 2. If (N-1) points are on the same line segment, then the "Fermat Point" is on the point which two lines join together. One is that the line segment, and the other is the one which passes the remaining point and\r perpendicular to the first line segment. 3. Now there are (M+N) points. Among them, M points will make a M jog-polygon. The others all drop in the polygon. As the diagram shown beneath, we know that the "Fermat Point" drops on the point which two lines join together. The two lines must pass as many points as possible. 所謂的「費馬點」是指三角形內到三頂點距離和最小的點。換言之,「費馬點」就是到平面上不共線三點距離和最小的點。因此,我們可定義,廣義的「費馬點」即是n 多邊形內到各頂點距離和最小的點,亦即到平面上不共線n 點距離和最小的點,但若平面上n 點不能恰為n 多邊形的頂點呢?這就是我們所要討論的。由於我們的靈感來自一份關於「費馬點」的科展作品,所以我們想到,當平面上n 點不能恰為n 凸多邊形的頂點,甚或其中有一部分的點共線時,將不能以n邊形的方法來探討,但我們可以將之化為m 邊形內(n-m)個點來討論。而更重要的是,我\r 們增加了另一個限制,重複的線段將不被我們列入計算。亦即當所求點落在某一多點共線的線段上時,我們只計算該線段的總長,而不計其中重複的較短線段。根據這個原則,我們試行證明平面上三點、四點、五點及六點的可能情況,期望能從中找出足以推廣至平面上n 點的一般性。結果雖不完美,但我們總算差強人意的歸納出了下列結論:1.若n 點共線段,所求點可為所共線段上任一點。2.若(n-1)點共線段,則由該不共線點引一線與共線段垂直,其交點即為所求。3.若(n+m)個點中有m 個點為一m 多邊形的頂點,另外n 個點落在該m 多邊形內,則由兩個外頂點引直線盡可能通過最多點,該兩直線的交點即為所求。

長方體內最少完全城堡數

我們試著尋找所需最小的城堡個數以看守整個a × b × c (a,b,c ? N) 的長方體。所謂城堡是一種棋子,當放置城堡的位置是(x, y, z) ,則(x, y,t)、(x,t, z)、(t, y, z) (t 是任何不超出邊界的正整數)是這個城堡可以看守的格子。我們用這些城堡來完全看守長方體,試著找出其最小值。在2005 年我們猜測了a = b = c 、a = b c 、a > b > c 的上界,而在2006 年時完成了a = b = c 、a = b c 的大部分情況的證明,少數不能解決的部份也提供了不錯的上界。目前我們在a = b = c 、a = b c 的情況幾乎完全解決,目前正在向a > b > c 的部份發展。A generalized searching method of finding the minimum number of castle which can oversee all over the rectangular box, defined as a × b× c (a,b,c ? N) , is presented. The castle here is defined as one kind of chess. The castle positioned as (x, y, z) can direct the lattice points of (x, y,t) 、(x,t, z) 、(t, y, z) (t is the positive integer and smaller than the box size). These castles we use here is to oversee the rectangular box and to help us to find the minimum number. In 2005, we got the upper bound of overseeing the rectangular box in the conditions of a = b = c、a = b c、a > b > c , while in 2006 we complete the proofs of the minimum number of castles based on the conditions of a = b = c 、a = b c . The further work we want to attain is to complete the case of a > b > c.

一個也沒漏掉,一個正有理數的排序的研究

本文中我們探討一個有趣的數列。這個數列有一個非常特殊的性質:將數列相鄰兩項的前項當分子,後項當分母,所產生的分數數列,恰好會出現所有的正有理數。 這個特殊的性質表示,可以將正有理數按照這個方式作排序,這個排序將完全不同於常見的正有理數排序的方法。 (1). 在正有理數的排序的結構中,我們做出許多有關於此數列的定理。 (2). 用數學歸納法證明此分數數列涵蓋所有正有理數,且每一正有理數只出現過一次。 (3). 將數列分割後,利用試算表製成數列規則表,並整理出快速的方法將數列表達出來。 (4). 將an 數列排成“樹"的模式,可更快速的把正有理數寫下來。 (5). 最後,設計出搜尋正有理數的演算法,解決在分數數列中第n個正有理數會是多少;以及正有理數會出現在數列中第幾項的問題。 Let’s discuss an interesting sequence. There is a very special quality in it. In this sequence, choose two numbers, which are close to each other, and suppose the first number as “member” while the second one as “denominator.” Then we can get a fraction sequence that includes all of the positive rational numbers! According to this special quality, we can arrange positive rational numbers by the following method. Then we can get a brand-new way of the arrangements. (1). We can find many theorems about this sequence according to this special arrangement of the positive rational numbers. (2). We can prove the rule that this fraction sequence includes all of the positive rational numbers by mathematical induction. Furthermore, every positive rational number appears only once. (3). After dividing this sequence into several parts, we can get a sequence rule list by using trial balance and find a faster method to express the sequence. (4). Arrange the an sequence by the tree model. By this way, we can get all of the positive rational numbers much faster. (5). Finally, we can develop the operation method to solve the questions that what position would one positive rational number be in the sequence and what is the first, second, third or nth positive rational number of the sequence.

A New 3-Dimensional Model for the Periodic Table of Codons

a. Purpose of research- Since the discovery of genetic codes and the dogma of 64 codons coding for 21 amino acids, scientists worldwide have been interested to know the reason(s) behind this unique number ratio (64:21). This ratio indicates certain form of inefficiency in the replication of amino acids. Such inefficiency can be explained through symmetries in the condons coding for the same amino acids. In the light of that, my project looks for patterns in the properties of amino acids and symmetries in the codons combinations. Using these analysis findings, I invented a three dimensional periodic table for the codons and amino acids that has a points to layers ratio of 64:21. b. Procedures- To get started with the project, I searched for relevant information in books and the Internet. After locating the relevant materials, I began my analysis by looking for non-random patterns in the correlation between codons and the respective amino acids they code for. At the same time, I try to look for symmetries in the codon distributions and suggest new and innovative models for a periodic table of codon combinations. I have come out with mainly a new model, with its own unique ideas and concepts behind it. Finally, I will try to match a property of the amino acids to the positions of the codons such that the table shows a gradual change in property of the amino acids, together with the symmetries. This will effectively explain the unique codons to amino acids ratio and lead to discovery of possible amino acids. c. Data- This research is primarily conducted based on the conventional 2D periodic table and no experimental data is collected. After much analysis, I have come up with the 3-sided triangular pyramid model. This model is inspired by the ratio of 64 codons coding for 21 amino acids, which can be easily approximated to 3:1. It is made up of a triangular pyramid that is three-faced, with the bottom side unutilized. As a triangular structure, each layer has dimensions in the multiples of 3. Layer 1 consists of 1 point, layer 2 with 3 points, layer 3 with 6 points and so on… until layer 7 with 18 points, having a total of 64 points. This 64 points to 21 layers ratio is consistent with the codons to amino acids ratio! d. Conclusions- The unique 64:21 ratio suggest certain form of inefficiency in the replication of amino acids. This may be explained through symmetries in condons coding for the same amino acids. A general 3:1 ratio can be approximated and this suggests a high possibility for the existence of a three-sided symmetry in codon combinations. Thus, this idea of a three-sided symmetry gives rise to my 3-sided triangular pyramid model. This new model of a 3-dimensional periodic table for codon combinations would be useful in explaining such a unique 64:21 ratio and serves to provide a basis for better understanding of the relationship between codons and amino acids. This new model may also lead to the discovery of currently unknown amino acids.

Dynamic Geometry and Problem Solving

Within the framework of the new educational model for mathematics based on constructivism, results are presented of the design, application, and evaluation processes of a series of didactic sequences aimed at developing the student’s abilities for problem solving as part of the geometry curriculum for technological preparatory schools, using the Cabri-Geometre II software. In this case, subjects of study were ten newly enrolled students from CETis 18 preparatory school in Mexicali, Baja California, Mexico. The theoretical basis for this work is the constructivist approach, mainly emphasizing Mashbits views (1997) regarding problem solving. This didactic proposal was longitudinally applied in a quasi-experimental qualitative design under the following analysis categories: problem solving skills and the impact of Cabri- Geometre II in geometry learning. Recognizing the potentiality this research can have with the proper follow-up, it is intended to include it in the preparatory school curricula. For this purpose, teachers should be trained to focus their work on learning instead of on teaching. As a result of this, designing educational programs will require for teachers to become more knowledgeable not only in discipline, but in the use of computer technology, the teaching process, learning, and the students themselves. The final objective of this project is to instill educators to play this new role. As a final point, conclusions on various psychological, pedagogical, and technological aspects are given placing emphasis on the creation of learning situations with their appropriate theoretical support. Using the Cabri-Geometre II as a resource, these situations will provide geometry teaching with a more dynamic and interesting concept applicable to real-life situations.

三角形之相似四分割

任意一個三角形要如何分割成四個彼此相似的組成三角形呢?我們透過嚴謹的數學推理,先對三角形作二、三分割的可能情形進行驗證,並藉由已完成相似二、三分割的三角形,運用「內分」和「外加」的觀念,使相似四分割的討論變得明快,並得以將各式三角形的所有相似四分割的圖示作完整而有系統的呈現。 \r 我們也對「比例四分割」的作圖法與其相關幾何性質,進行猜想與討論,並驗證得出一些結果。尤其對「黃金三角形」經比例四分割後,組成三角形之對應邊長的比值也是「黃金值」,以及使用五條摺痕線的摺紙方式,可以摺出一張黃金三角形紙張的比例四分割,這些研究結果都令我們感到獲益良多。 How to divide a triangle into four similar little triangles? Possible situations of dividing a triangle into two or three parts could be testified by strict mathematical inferences, and then the concepts of “internal division” and “external addition” could be applied to make our discussion clearly and briefly. With above discussions, figures about four similar divisions of all kinds of triangles could be presented completely and systematically. Some results were come up after making some conjectures and discussions about the geometric constructions and geometric properties of “four proportional divisions”. We learn a lot by these researches especially on the discoveries that the ratio of those corresponding sides in each four similar triangles which form a golden triangle, is also golden ratio; and that we could divide a golden triangle into four similar triangles by using five folding lines.

數形合一

這份研究是關於一個「數形合一」的問題,研究的主要目的是找出同時具有兩種圖形數身分以上的數。研究結果發現雙重多角數必定存在,但個數可能有限個也可能無限多個,有些雙重中心多角數是有限多個,有些雙重中心多角數是無限多個,但令人意外的是同時是K角數和中心K角數的數卻皆是永遠是無限多個,我對其模式進行了探究並加以具體分類,並說明原因。研究過程中發現遞推關係可以大大簡化計算的步驟,可簡潔快速的求出這些數。我也證明了同時是三、四、五角數的數只有 1。此外,我將研究應用在熱門的平衡數(balancing numbers)和NSW數(NSW numbers)等上面,應用多角數的研究解決一些熱門的問題和找出了圖形上不證自明的結果。