Kepler Insert Englisch 4

Total Page:16

File Type:pdf, Size:1020Kb

Kepler Insert Englisch 4 investigations into flat tessellations with pentagons, pentagons, with tessellations flat into investigations Internet: www.zometool.com Internet: with regular pentagons (Zometool’s red plane). His His plane). red (Zometool’s pentagons regular with Tel.: +49 (0)8324-9336040 · Mail: [email protected] [email protected] Mail: · (0)8324-9336040 +49 Tel.: ) and of tessellations of and ) kit Ice Crystals and Stars and Crystals Ice Kepler’s Kosmos Kepler’s hexagonal structure of snowflakes (see Zometool (see snowflakes of structure hexagonal Zometool Europa UG · Rainbühlgasse 7 · D 87541 Bad Hindelang Bad 87541 D · 7 Rainbühlgasse · UG Europa Zometool b c a Kepler’s further works include the study of the the of study the include works further Kepler’s Zometool Universum. Zometool in the extensive and versatile and extensive the in composition, Harmonie der Welt. der Harmonie composition, “: just a small taste of the many possibilities many the of taste small a just “: „ and “ „ “, „ Creator 3 Creator 5 design Hyperdo a “Copernican revolution” in the material sciences. material the in revolution” “Copernican a created a musical monument to Kepler with his 1957 1957 his with Kepler to monument musical a created with Dan Schechtman’s discovery of quasicrystals, which prompted which quasicrystals, of discovery Schechtman’s Dan with mechanics and the “music” of the universe. Paul Hindemith Hindemith Paul universe. the of “music” the and mechanics blocks have experienced an exciting revival during the 20th century, 20th the during revival exciting an experienced have blocks in which Kepler explains not only the mathematics, but also the the also but mathematics, the only not explains Kepler which in Penrose tiles can cover a plane surface quasiperiodically. Kepler quasiperiodically. surface plane a cover can tiles Penrose is a brilliant and daring “Theory of Everything”, Everything”, of “Theory daring and brilliant a is Harmonicus Mundi Harmonicus Kepler blocks will fill space according to matching rules, just as just rules, matching to according space fill will blocks Kepler first systematic documentation of mathematical tessellations. mathematical of documentation systematic first constructed with two types of “squashed” cubes (parallelepipeds). cubes “squashed” of types two with constructed discovered two new non-convex polyhedrons and compiled the compiled and polyhedrons non-convex new two discovered “squashed” squares (parallelograms), the triacontahedron can be can triacontahedron the (parallelograms), squares “squashed” He proved that there are 13 half-regular Archimedean solids, Archimedean half-regular 13 are there that proved He variations of Richert tilings. While Richert’s tiles are two types of types two are tiles Richert’s While tilings. Richert of variations treasure trove of both 2-dimensional and 3-dimensional geometry. 3-dimensional and 2-dimensional both of trove treasure its sub-units (Kepler blocks), which are a 3-dimensional a are which blocks), (Kepler sub-units its 1619. It contains a more precise model of the cosmos and is a is and cosmos the of model precise more a contains It 1619. Kepler also discovered the rhombic triacontahedron and and triacontahedron rhombic the discovered also Kepler (The Harmony of the World), which he published in published he which World), the of Harmony (The Mundi Richert and Sir Roger Penrose in the 20th century. 20th the in Penrose Roger Sir and Richert Sun Johannes Kepler described his third theory in in theory third his described Kepler Johannes other Zometool kits. kits. Zometool other Harmonicus Harmonicus decagons and stars heralded the tilings of Clark Clark of tilings the heralded stars and decagons The components of Kepler’s Kosmos are naturally compatible with all with compatible naturally are Kosmos Kepler’s of components The Richart and Penrose. Penrose. and Richart b c , Kepler, with large and small Richart diamonds (yellow), (yellow), diamonds Richart small and large with Kepler, , below: below: Tiling a TOOL ZOME TOOL ZOME , + arranged to form a rhombic triacontahedron. rhombic a form to arranged + , above: 3 Kepler blocks Kepler 2 1 to the cube of the semi-major axis of its orbit. its of axis semi-major the of cube the to The square of the orbital period of a planet is directly proportional directly is planet a of period orbital the of square The . 3 ® ® equal intervals of time. of intervals equal art and science at play at science and art art and science at play at science and art A line joining a planet and the sun sweeps out equal areas during areas equal out sweeps sun the and planet a joining line A . 2 The orbit of every planet is an ellipse with the sun at one focus. one at sun the with ellipse an is planet every of orbit The . 1 3 2 1 : : Kepler’s Laws of Planetary Motion Planetary of Laws Kepler’s art and science at play The flash of light: Kepler believed that God had given ® him a sign and that he had discovered the “key to the universe”. Kepler summised that the numerical ratio between the orbits of neighbouring planets would be ZOMETOOL similar to the sphere radius of the regular multi-sided solids (polyhedrons) - ie: that of the inscribed sphere At the beginning of the 17th. century, the world was above: Kepler’s illustrations of the Platonic Solids from the Mysterium Cosmographicum, 1596: above: Zometool models of the five Platonic Solids, corresponding to Kepler’s vision of the universe: to the circumscribed sphere. in turmoil. The Thirty Years’ War was decimating Cube - earth, Tetrahedron - fire, Dodecahedron - universum, Icosahedron - water, Octahedron - air. Icosahedron, Octahedron, Tetrahedron, Cube und Dodecahedron. Germany and the Netherlands were embroiled in far left: quill illustration of the moon, from Sidereus Nuncius, Galileo Galilei, 1610. the struggle for independance from Spain; ancient Kepler was born in Weil der Stadt; a sickly child, whose sight was Kepler’s theory stated that if a particular regular polyhedron were Kepler in Prag practices such as herbology, witchcraft and astrology marred by smallpox at an early age. He worked at his mother’s to by placed within the orbit of a planet, the sphere which exactly The Danish astrologer, Tycho Brahe, invited Kepler to work with continued to flourish amidst breathtaking advances inn, drew maps and attended a school for latin and the grammar surrounded this solid would then, by definition, describe the orbit him in Prag. It is probable that Brahe was interested in Kepler’s in science and technology. Hugo Grotius’ book, Das school in Maulbronn. He was a gifted child and graduated from of the next planet. Kepler took the orbit of the earth as the deter- mathematical skills, hoping that these would complement his freie Meer (The Freedom of the Seas) - the basis of our his theology course at the University of Tübingen at the early mining factor for all subsequent orbits. It was an elegant solution: own precise observations. Following Brahe’s death a year later, current conception of civil-rights - was banned by the Pope age of 20. During this time, he studied Copernicus’ vision of at that time, there were only six known planets and the Greeks the Holy Roman Emporer Rudolf II, a Habsburger, appointed immediately after publication, whilst in England Shakespeare’s the world and, at 23, renounced his plan to become a protestant had discovered that there are only five polyhedrons. Kepler Kepler to be his court mathematician in Prag. Kepler therefore Sonnettes were being received with great acclaim. priest in order to take up a professorship for mathematics at tested this theory, using Copernicus’ calculations as a basis and “inherited” Brahe’s extensive works, with which he hoped to Graz. He became more and more interested in the work of the result showed a discrepancy of less than 10%... Even by improve his own earlier theories. The measurements did not In March 1609 in Prag, Johannes Kepler, mathematician to the Copernicus and realised that he had stumbled upon an today’s standards, a quite stunning success. comform and he was forced to abandon his attempt. He began Holy Roman Emporer Rudolf II, presented his master with a heavy untapped treasure. Kepler began searching for a system work on an astrological system which was not based on the book. His work, Astronomia Nova, subtitled Physica Coelestis, behind the relationships of the distances between the Kepler’s cosmological theory, later published under the planetary orbits. In 1609, Kepler published Astronomia Nova, (Physics of the Heavens), marked the beginning of a new era. planets and the sun, hoping to discover a “construction title Mysterium Cosmographicum (The Secret of the a book which contains the first and second of Kepler’s Laws. plan of the world”. He sought harmony and intrinsic Universe) was born. Despite a life filled with trouble and personal tragedy, Kepler’s coherence, believing that God’s works, like our architecture, Kepler’s Kosmos contribution in many very different fields, such as astronomy, must be subject to rules and regulations. He hoped to find the It is the beginning cosmology, optics, arithmetic and geometry, is significant. solution in geometry. of a new era..
Recommended publications
  • A New Calculable Orbital-Model of the Atomic Nucleus Based on a Platonic-Solid Framework
    A new calculable Orbital-Model of the Atomic Nucleus based on a Platonic-Solid framework and based on constant Phi by Dipl. Ing. (FH) Harry Harry K. K.Hahn Hahn / Germany ------------------------------ 12. December 2020 Abstract : Crystallography indicates that the structure of the atomic nucleus must follow a crystal -like order. Quasicrystals and Atomic Clusters with a precise Icosahedral - and Dodecahedral structure indi cate that the five Platonic Solids are the theoretical framework behind the design of the atomic nucleus. With my study I advance the hypothesis that the reference for the shell -structure of the atomic nucleus are the Platonic Solids. In my new model of the atomic nucleus I consider the central space diagonals of the Platonic Solids as the long axes of Proton - or Neutron Orbitals, which are similar to electron orbitals. Ten such Proton- or Neutron Orbitals form a complete dodecahedral orbital-stru cture (shell), which is the shell -type with the maximum number of protons or neutrons. An atomic nucleus therefore mainly consists of dodecahedral shaped shells. But stable Icosahedral- and Hexagonal-(cubic) shells also appear in certain elements. Consta nt PhI which directly appears in the geometry of the Dodecahedron and Icosahedron seems to be the fundamental constant that defines the structure of the atomic nucleus and the structure of the wave systems (orbitals) which form the atomic nucelus. Albert Einstein wrote in a letter that the true constants of an Universal Theory must be mathematical constants like Pi (π) or e. My mathematical discovery described in chapter 5 shows that all irrational square roots of the natural numbers and even constant Pi (π) can be expressed with algebraic terms that only contain constant Phi (ϕ) and 1 Therefore it is logical to assume that constant Phi, which also defines the structure of the Platonic Solids must be the fundamental constant that defines the structure of the atomic nucleus.
    [Show full text]
  • The Roundest Polyhedra with Symmetry Constraints
    Article The Roundest Polyhedra with Symmetry Constraints András Lengyel *,†, Zsolt Gáspár † and Tibor Tarnai † Department of Structural Mechanics, Budapest University of Technology and Economics, H-1111 Budapest, Hungary; [email protected] (Z.G.); [email protected] (T.T.) * Correspondence: [email protected]; Tel.: +36-1-463-4044 † These authors contributed equally to this work. Academic Editor: Egon Schulte Received: 5 December 2016; Accepted: 8 March 2017; Published: 15 March 2017 Abstract: Amongst the convex polyhedra with n faces circumscribed about the unit sphere, which has the minimum surface area? This is the isoperimetric problem in discrete geometry which is addressed in this study. The solution of this problem represents the closest approximation of the sphere, i.e., the roundest polyhedra. A new numerical optimization method developed previously by the authors has been applied to optimize polyhedra to best approximate a sphere if tetrahedral, octahedral, or icosahedral symmetry constraints are applied. In addition to evidence provided for various cases of face numbers, potentially optimal polyhedra are also shown for n up to 132. Keywords: polyhedra; isoperimetric problem; point group symmetry 1. Introduction The so-called isoperimetric problem in mathematics is concerned with the determination of the shape of spatial (or planar) objects which have the largest possible volume (or area) enclosed with given surface area (or circumference). The isoperimetric problem for polyhedra can be reflected in a question as follows: What polyhedron maximizes the volume if the surface area and the number of faces n are given? The problem can be quantified by the so-called Steinitz number [1] S = A3/V2, a dimensionless quantity in terms of the surface area A and volume V of the polyhedron, such that solutions of the isoperimetric problem minimize S.
    [Show full text]
  • Of Great Rhombicuboctahedron/Archimedean Solid
    Mathematical Analysis of Great Rhombicuboctahedron/Archimedean Solid Mr Harish Chandra Rajpoot M.M.M. University of Technology, Gorakhpur-273010 (UP), India March, 2015 Introduction: A great rhombicuboctahedron is an Archimedean solid which has 12 congruent square faces, 8 congruent regular hexagonal faces & 6 congruent regular octagonal faces each having equal edge length. It has 72 edges & 48 vertices lying on a spherical surface with a certain radius. It is created/generated by expanding a truncated cube having 8 equilateral triangular faces & 6 regular octagonal faces. Thus by the expansion, each of 12 originally truncated edges changes into a square face, each of 8 triangular faces of the original solid changes into a regular hexagonal face & 6 regular octagonal faces of original solid remain unchanged i.e. octagonal faces are shifted radially. Thus a solid with 12 squares, 8 hexagonal & 6 octagonal faces, is obtained which is called great rhombicuboctahedron which is an Archimedean solid. (See figure 1), thus we have Figure 1: A great rhombicuboctahedron having 12 ( ) ( ) congruent square faces, 8 congruent regular ( ) ( ) hexagonal faces & 6 congruent regular octagonal faces each of equal edge length 풂 ( ) ( ) We would apply HCR’s Theory of Polygon to derive a mathematical relationship between radius of the spherical surface passing through all 48 vertices & the edge length of a great rhombicuboctahedron for calculating its important parameters such as normal distance of each face, surface area, volume etc. Derivation of outer (circumscribed) radius ( ) of great rhombicuboctahedron: Let be the radius of the spherical surface passing through all 48 vertices of a great rhombicuboctahedron with edge length & the centre O.
    [Show full text]
  • A Technology to Synthesize 360-Degree Video Based on Regular Dodecahedron in Virtual Environment Systems*
    A Technology to Synthesize 360-Degree Video Based on Regular Dodecahedron in Virtual Environment Systems* Petr Timokhin 1[0000-0002-0718-1436], Mikhail Mikhaylyuk2[0000-0002-7793-080X], and Klim Panteley3[0000-0001-9281-2396] Federal State Institution «Scientific Research Institute for System Analysis of the Russian Academy of Sciences», Moscow, Russia 1 [email protected], 2 [email protected], 3 [email protected] Abstract. The paper proposes a new technology of creating panoramic video with a 360-degree view based on virtual environment projection on regular do- decahedron. The key idea consists in constructing of inner dodecahedron surface (observed by the viewer) composed of virtual environment snapshots obtained by twelve identical virtual cameras. A method to calculate such cameras’ projec- tion and orientation parameters based on “golden rectangles” geometry as well as a method to calculate snapshots position around the observer ensuring synthe- sis of continuous 360-panorama are developed. The technology and the methods were implemented in software complex and tested on the task of virtual observing the Earth from space. The research findings can be applied in virtual environment systems, video simulators, scientific visualization, virtual laboratories, etc. Keywords: Visualization, Virtual Environment, Regular Dodecahedron, Video 360, Panoramic Mapping, GPU. 1 Introduction In modern human activities the importance of the visualization of virtual prototypes of real objects and phenomena is increasingly grown. In particular, it’s especially required for training specialists in space and aviation industries, medicine, nuclear industry and other areas, where the mistake cost is extremely high [1-3]. The effectiveness of work- ing with virtual prototypes is significantly increased if an observer experiences a feeling of being present in virtual environment.
    [Show full text]
  • A Method for Predicting Multivariate Random Loads and a Discrete Approximation of the Multidimensional Design Load Envelope
    International Forum on Aeroelasticity and Structural Dynamics IFASD 2017 25-28 June 2017 Como, Italy A METHOD FOR PREDICTING MULTIVARIATE RANDOM LOADS AND A DISCRETE APPROXIMATION OF THE MULTIDIMENSIONAL DESIGN LOAD ENVELOPE Carlo Aquilini1 and Daniele Parisse1 1Airbus Defence and Space GmbH Rechliner Str., 85077 Manching, Germany [email protected] Keywords: aeroelasticity, buffeting, combined random loads, multidimensional design load envelope, IFASD-2017 Abstract: Random loads are of greatest concern during the design phase of new aircraft. They can either result from a stationary Gaussian process, such as continuous turbulence, or from a random process, such as buffet. Buffet phenomena are especially relevant for fighters flying in the transonic regime at high angles of attack or when the turbulent, separated air flow induces fluctuating pressures on structures like wing surfaces, horizontal tail planes, vertical tail planes, airbrakes, flaps or landing gear doors. In this paper a method is presented for predicting n-dimensional combined loads in the presence of massively separated flows. This method can be used both early in the design process, when only numerical data are available, and later, when test data measurements have been performed. Moreover, the two-dimensional load envelope for combined load cases and its discretization, which are well documented in the literature, are generalized to n dimensions, n ≥ 3. 1 INTRODUCTION The main objectives of this paper are: 1. To derive a method for predicting multivariate loads (but also displacements, velocities and accelerations in terms of auto- and cross-power spectra, [1, pp. 319-320]) for aircraft, or parts of them, subjected to a random excitation.
    [Show full text]
  • Bridges Conference Proceedings Guidelines
    Proceedings of Bridges 2013: Mathematics, Music, Art, Architecture, Culture Exploring the Vertices of a Triacontahedron Robert Weadon Rollings 883 Brimorton Drive, Scarborough, Ontario, M1G 2T8 E-mail: [email protected] Abstract The rhombic triacontahedron can be used as a framework for locating the vertices of the five platonic solids. The five models presented here, which are made of babinga wood and brass rods illustrate this relationship. Introduction My initial interest in the platonic solids began with the work of Cox [1]. My initial explorations of the platonic solids lead to the series of models Polyhedra through the Beauty of Wood [2]. I have continued this exploration by using a rhombic triacontahedron at the core of my models and illustrating its relationship to all five platonic solids. Rhombic Triacontahedron The rhombic triacontahedron has 30 rhombic faces where the ratio of the diagonals is the golden ratio. The models shown in Figures 1, 2, 4, and 5 illustrate that the vertices of an icosahedron, dodecahedron, hexahedron and tetrahedron all lie on the circumsphere of the rhombic triacontahedron. In addition, Figure 3 shows that the vertices of the octahedron lie on the inscribed sphere of the rhombic triacontahedron. Creating the Models Each of the five rhombic triacontahedrons are made of 1/4 inch thick babinga wood. The edges of the rhombi were cut at 18 degrees on a band saw. After the assembly of the triacontahedron 1/8 inch brass rods were inserted a specific vertices and then fitted with 1/2 inch cocabola wood spheres. Different vertices (or faces in the case of the octahedron) were chosen for each platonic solid.
    [Show full text]
  • Polytopes and Nuclear Structure by Roger Ellman Abstract
    Polytopes and Nuclear Structure by Roger Ellman Abstract While the parameters Z and A indicate a general structural pattern for the atomic nuclei, the exact nuclear masses in their fine differences appear to vary somewhat randomly, seem not to exhibit the orderly kind of logical system that nature must exhibit. It is shown that separation energy [the mass of the nucleus before decay less the mass of a decay’s products], not mass defect [the sum of the nuclear protons and neutrons masses less the nuclear mass], is the “touchstone” of nuclear stability. When not part of an atomic nucleus the neutron decays into a proton and an electron indicating that it can be deemed a combination of those two. Considering that, the nucleus can be analyzed as an assembly of A protons and N = A - Z electrons, where N of the protons form neutrons with the N electrons. Resulting analysis discloses a comprehensive orderly structure among the actual nuclear masses of all the nuclear types and isotopes. The analysis examines in detail the conditions for nuclear stability / instability. An interesting secondary component of that analysis and the resulting logical order is the family of geometric forms called polytopes, in particular the regular polyhedrons. Roger Ellman, The-Origin Foundation, Inc. http://www.The-Origin.org 320 Gemma Circle, Santa Rosa, CA 95404, USA [email protected] 1 Polytopes and Nuclear Structure Roger Ellman While the parameters, Z and A, of atomic nuclei indicate a general structural pattern for the nuclei, the exact nuclear masses in their various differences seem not to exhibit the orderly kind of logical system that nature must exhibit.
    [Show full text]
  • Complementary Relationship Between the Golden Ratio and the Silver
    Complementary Relationship between the Golden Ratio and the Silver Ratio in the Three-Dimensional Space & “Golden Transformation” and “Silver Transformation” applied to Duals of Semi-regular Convex Polyhedra September 1, 2010 Hiroaki Kimpara 1. Preface The Golden Ratio and the Silver Ratio 1 : serve as the fundamental ratio in the shape of objects and they have so far been considered independent of each other. However, the author has found out, through application of the “Golden Transformation” of rhombic dodecahedron and the “Silver Transformation” of rhombic triacontahedron, that these two ratios are closely related and complementary to each other in the 3-demensional space. Duals of semi-regular polyhedra are classified into 5 patterns. There exist 2 types of polyhedra in each of 5 patterns. In case of the rhombic polyhedra, they are the dodecahedron and the triacontahedron. In case of the trapezoidal polyhedral, they are the icosidodecahedron and the hexecontahedron. In case of the pentagonal polyhedra, they are icositetrahedron and the hexecontahedron. Of these 2 types, the one with the lower number of faces is based on the Silver Ratio and the one with the higher number of faces is based on the Golden Ratio. The “Golden Transformation” practically means to replace each face of: (1) the rhombic dodecahedron with the face of the rhombic triacontahedron, (2) trapezoidal icosidodecahedron with the face of the trapezoidal hexecontahedron, and (3) the pentagonal icositetrahedron with the face of the pentagonal hexecontahedron. These replacing faces are all partitioned into triangles. Similarly, the “Silver Transformation” means to replace each face of: (1) the rhombic triacontahedron with the face of the rhombic dodecahedron, (2) trapezoidal hexecontahedron with the face of the trapezoidal icosidodecahedron, and (3) the pentagonal hexecontahedron with the face of the pentagonal icositetrahedron.
    [Show full text]
  • Volume 7 2007
    FORUM GEOMETRICORUM A Journal on Classical Euclidean Geometry and Related Areas published by Department of Mathematical Sciences Florida Atlantic University b b b FORUM GEOM Volume 7 2007 http://forumgeom.fau.edu ISSN 1534-1178 Editorial Board Advisors: John H. Conway Princeton, New Jersey, USA Julio Gonzalez Cabillon Montevideo, Uruguay Richard Guy Calgary, Alberta, Canada Clark Kimberling Evansville, Indiana, USA Kee Yuen Lam Vancouver, British Columbia, Canada Tsit Yuen Lam Berkeley, California, USA Fred Richman Boca Raton, Florida, USA Editor-in-chief: Paul Yiu Boca Raton, Florida, USA Editors: Clayton Dodge Orono, Maine, USA Roland Eddy St. John’s, Newfoundland, Canada Jean-Pierre Ehrmann Paris, France Chris Fisher Regina, Saskatchewan, Canada Rudolf Fritsch Munich, Germany Bernard Gibert St Etiene, France Antreas P. Hatzipolakis Athens, Greece Michael Lambrou Crete, Greece Floor van Lamoen Goes, Netherlands Fred Pui Fai Leung Singapore, Singapore Daniel B. Shapiro Columbus, Ohio, USA Steve Sigur Atlanta, Georgia, USA Man Keung Siu Hong Kong, China Peter Woo La Mirada, California, USA Technical Editors: Yuandan Lin Boca Raton, Florida, USA Aaron Meyerowitz Boca Raton, Florida, USA Xiao-Dong Zhang Boca Raton, Florida, USA Consultants: Frederick Hoffman Boca Raton, Floirda, USA Stephen Locke Boca Raton, Florida, USA Heinrich Niederhausen Boca Raton, Florida, USA Table of Contents Joseph Stern, Euler’s triangle determination problem, 1 Christopher Bradley, David Monk, and Geoff Smith, On a porism associated with the Euler and Droz-Farny lines, 11 Yu-Dong Wu and Zhi-Hua Zhang, The edge-tangent sphere of a circumscriptible tetrahedron, 19 Melissa Baker and Robert Powers, A stronger triangle inequality for neutral geometry, 25 Jingcheng Tong and Sidney Kung, A simple construction of the golden ratio, 31 Tom M.
    [Show full text]
  • Solid Geometry Geometry 10.1 Vocabulary and More Drawing!
    Solid Geometry Geometry 10.1 Vocabulary and More Drawing! A polyhedron is a geometric solid made up of polygon faces which meet at straight-line edges that come together at vertices. Like polygons, polyheda are named with prefixes we have already used. Octahedron = 8 sides. Hexahedron = 6 sides. The only exception is the Tetrahedron, which has four sides (it is not called a quadrahedron). Polyhedra can be regular or irregular. Name the two figures above. Draw: 1. A regular hexahedron and two irregular hexahedra. 2. A hexahedral pyramid. Give a better name to this figure. 3. A rectangular prism. There are five regular convex polyhedra, referred to as the Platonic Solids. Tetrahedron Cube Octahedron Dodecahedron Icosahedron Prisms and Pyramids Geometry 10.1 Prisms: Congruent bases connected by lateral faces which are paral- lelograms. If the lateral faces are rectangles, the prism is called a right prism. If the lateral faces are not rectangles, the prism is called oblique. Altitude Pyramids: A single base connected by triangular lateral faces which meet at a point. A pyramid is right if the apex is aligned above the centroid of its base. A pyramid is oblique if its apex is not centered above its base. Altitude A cylinder is similar to a prism, with a circular base. The line connecting the centers of the bases is called the axis. Cylinders may be right or oblique. In a right cylinder the _______ is perpendicular to the ______. A cone is similar to a pyramid with a circular base. Cones may be right or oblique. The altitude of a right cone connects the center of the base to its apex.
    [Show full text]
  • SURFACE-AREA-MINIMIZING N-HEDRAL TILES
    SURFACE-AREA-MINIMIZING n-HEDRAL TILES WHAN GHANG, ZANE MARTIN, AND STEVEN WARUHIU ABSTRACT. We provide a list of conjectured surface-area-minimizing n-hedral tiles of space for n from 4 to 14, previously known only for n equal to 5 or 6. We find the optimal "orientation-preserving" tetrahedral tile (n = 4), and we give a nice proof for the optimal 5-hedron (a triangular prism). 1. INTRODUCTION For fixed n, we seek a unit-volume n-hedral tile of space that minimizes surface area. Our Conjecture 2.1 provides candidates from n = 4, a certain irregular tetrahedron, to n ≥ 14, Kelvin’s truncated octahe- dron (see Figs. 1-7). The conjecture is known for n = 6 and n = 5. That the cube is the best 6-hedron, tile or not, is well known [FT] (See Thm. 2.3). Theorem 3.4 shows that among convex polyhedra, for fixed n, there exists a surface-area-minimizing n-hedral tile of space. Section 4 gives some properties of prisms and a proof that a certain hexagonal prism is the surface-area-minimizing prism. Theorem 5.10 gives a nice new proof that a certain triangular prism is the surface-area-minimizing 5-hedron. Theorem 5.2 proves that a third of a triangular prism is the surface-area-minimizing "orientation-preserving" 4- hedral tile, based on a classification of tetrahedral tiles by Sommerville [So]. (Unfortunately the regular tetrahedron does not tile space.) 1.1. Acknowledgements. This paper is work of the 2012 “SMALL” Geometry Group, an undergraduate research group at Williams College continued by Waruhiu.
    [Show full text]
  • A Mediaeval Arabic Addendum to Euclid's Elements
    SCIAMVS 9 (2008), 133–209 Book XVI: A Mediaeval Arabic Addendum To Euclid’s Elements Gregg De Young Mathematics Department The American University in Cairo [email protected] I Introduction Euclid’s Elements has been transmitted into many languages since it was first com- posed in Greek and has provoked extensive discussions in many branches of this transmission. The Arabic transmission was no exception. Once it became available in Arabic during the eighth and ninth centuries, Euclid’s mathematical classic was “corrected”, summarized, given addenda, reduced to extracts, commented upon in whole and in part, given alternate demonstrations, paraphrased, and much more. These discussions were not limited to any specific time period, but continued to appear regularly until the nineteenth and twentieth centuries. This paper presents a hitherto unstudied addendum to an edited version of a popular Euclidean treatise. The addendum, entitled Book XVI, comprises nineteen propositions describing techniques for constructing polyhedra within other polyhe- dra or within spheres. Thus it develops themes related to those of book XV, itself a late Greek addendum to the genuine Euclidean treatise. The contents are, how- ever, in the tradition of Archimedes rather than Euclid. The first part of Book XVI describes construction of semiregular truncated polyhedra inscribed within regular polyhedra (Platonic solids) and within spheres. The addendum ends with what may be the earliest discussion of the construction of a representative example from each of the classes of semiregular polyhedra known today as prisms and antiprisms. Thus, although the editor or copyist who attached this book XVI to the manuscript clearly intended this material as a kind of continuation of the Elements, the intention of the original author is less clearly Euclidean.
    [Show full text]