The Law of Sines and Cosines of the Orthocentric Tetrahedron with 4-State and Its Substitution Algorithm—Application of Pythagorean Theorem of Four Dimensional Volume (Formula 6)

2019 ◽  
Vol 09 (10) ◽  
pp. 1174-1186 ◽  
Author(s):  
国伟 蔡
2018 ◽  
Vol 6 (3) ◽  
pp. 385-396
Author(s):  
Sendi Ramdhani

AbstrakPenelitian ini bertujuan untuk menyelidiki kemampuan penalaran analogis santri dalam geometri dan mengidentifikasi kesulitan dan hambatan mereka. Penulis mendeskripsikan bagaimana kemampuan analogis dalam pemahaman konsep geometri, kemampuan penalaran analogis dalam teorema dan sifat, dan kemampunan penalaran analogis dalam masalah geometri. Penelitian ini merupakan bagian dari pengembangan bahan ajar geometri untuk meningkatkan kemampuan penalaran analogis santri. Adapun metode penelitiannya menggunakan penelitian kualitatif dalam materi teorema Pythagoras, aturan kosinus, dan teorema garis tinggi segitiga yang melibatkan 80 santri di sebuah Pondok Pesantren di Bandung, Indonesia. Hasil dari penelitian ini menemukan bahwa kemampuan penalaran analogis santri berada di kategori rendah dan cukup. Berdasarkan hasil tes dan wawancara menunjukkan santri kesulitan menuliskan persamaan Pythagoras berdasarkan gambar segitiga siku-siku dalam berbagai konteks, menuliskan persamaan kosinus berdasarkan definisi verbal dan gambar, melukis segitiga siku-siku berdasarkan persamaan Pythagoras, melakukan penalaran analogis antara teorema Pythagoras dan aturan kosinus, dan melakukan penalaran analogis berdasarkan teorema. Rekomendasi dari penelitian ini berupa kesulitan-kesulitan dan kelemahan-kelemahan santri dalam kemampuan penalaran analogis yang akan menjadi landasan untuk mengembangan bahan ajar geometri. AbstractThis study aims to investigate the analogical reasoning ability of santri in geometry and identify their difficulties and constraints. The author describes how analogical reasoning in understanding the concepts of geometry, analogical reasoning in theorems and properties, and the use of analogical reasoning in geometry problems. This research is part of the development of geometry teaching materials to improve the analogical reasoning ability of santri. The research method uses qualitative research in the material of Pythagoras theorem, the law of cosine, and triangle altitude theorem that involves 80 santri at a Pondok Pesantren in Bandung, Indonesia. The results of this study found that the santri's analogical reasoning abilities were in the low and sufficient category. Based on the results of the tests and interviews it is difficult for students to write Pythagoras equations based on right triangle images in various contexts, writing cosine equations based on verbal definitions and drawings, painting right triangles based on Pythagoras equations, analogical reasoning between Pythagorean theorem and cosine rules; doing analogical reasoning based on the theorem. The recommendation of this research is the difficulties and weaknesses of santri in analogical reasoning ability that will be the basis for developing geometry teaching materials.


2018 ◽  
Vol 102 (553) ◽  
pp. 77-88
Author(s):  
Matúš Harminc ◽  
Lucia Janičková

The following observations are motivated by the facts that the area of a planar figure displayed on a screen can be expressed by a certain number of pixels; and if the figure is drawn by a plotter, then its area can be characterised by the total length of a line which fills it in.The generalisations of the Pythagorean theorem are of three kinds. Firstly, the squares on the sides of the right triangle are substituted by other geometrically similar planar figures (Euclid's Elements Book VI, Proposition 31 [1]). Secondly, the assumption of the right angle is omitted (the law of cosines), or both of these generalizations occur simultaneously (Pappus’ area theorem [2], see also H. W. Eves [3]). Thirdly, mathematical spaces other than the plane are considered (for example, de Gua-Faulhaber theorem about trirectangular tetrahedra [3], further generalised by Tinseau [4], Euclideann-spaces, Banach spaces [5], see also [6]).


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