Polyhedra

Rectified truncated icosahedron

In geometry, the rectified truncated icosahedron is a convex polyhedron. It has 92 faces: 60 isosceles triangles, 12 regular pentagons, and 20 regular hexagons. It is constructed as a rectified, truncated icosahedron, rectification truncating vertices down to mid-edges. As a near-miss Johnson solid, under icosahedral symmetry, the pentagons are always regular, although the hexagons, while having equal edge lengths, do not have the same edge lengths with the pentagons, having slightly different but alternating angles, causing the triangles to be isosceles instead. The shape is a symmetrohedron with notation I(1,2,*,[2]) (Wikipedia).

Rectified truncated icosahedron
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Rectified Tesseract

This shows a 3d print of a mathematical sculpture I produced using shapeways.com. This model is available at http://shpws.me/2Uh3

From playlist 3D printing

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How to Construct an Icosahedron

How the greeks constructed the icosahedron. Source: Euclids Elements Book 13, Proposition 16. In geometry, a regular icosahedron is a convex polyhedron with 20 faces, 30 edges and 12 vertices. It is one of the five Platonic solids, and the one with the most faces. https://www.etsy.com/lis

From playlist Platonic Solids

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Regular polyhedra

This shows a 3d print of a mathematical sculpture I produced using shapeways.com. This model is available at http://shpws.me/q0PF.

From playlist 3D printing

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How to Construct a Dodecahedron

How the greeks constructed the Dodecahedron. Euclids Elements Book 13, Proposition 17. In geometry, a dodecahedron is any polyhedron with twelve flat faces. The most familiar dodecahedron is the regular dodecahedron with regular pentagons as faces, which is a Platonic solid. A regular dode

From playlist Platonic Solids

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Rubenstein's cactus

Joint work with Rick Rubenstein. Available from Shapeways at http://shpws.me/r1iO

From playlist 3D printing

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Geodesic domes and spheres

Geodesic domes: http://shpws.me/qrM2 Geodesic spheres: http://shpws.me/qrM3

From playlist 3D printing

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Octahedron Fractal Graph

This shows a 3d print of a mathematical sculpture I produced using shapeways.com. This model is available at http://shpws.me/19O1

From playlist 3D printing

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Platonic and Archimedean solids

Platonic solids: http://shpws.me/qPNS Archimedean solids: http://shpws.me/qPNV

From playlist 3D printing

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32 and Truncated Icosahedron - Numberphile

The 32-sided truncated icosahedron forms the basis of many footballs (soccer balls!). It's also a big deal in chemistry. More links & stuff in full description below ↓↓↓ sixtysymbols video on footballs: http://www.youtube.com/watch?v=55M1cq62m2c periodicvideos video on buckyballs: http://

From playlist Football (soccer) on Numberphile

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How to construct a Tetrahedron

How the greeks constructed the first platonic solid: the regular tetrahedron. Source: Euclids Elements Book 13, Proposition 13. In geometry, a tetrahedron also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. Th

From playlist Platonic Solids

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The remarkable Platonic solids II: symmetry | Universal Hyperbolic Geometry 48 | NJ Wildberger

We look at the symmetries of the Platonic solids, starting here with rigid motions, which are essentially rotations about fixed axes. We use the normalization of angle whereby one full turn has the value one, and also connect the number of rigid motions with the number of directed edges.

From playlist Universal Hyperbolic Geometry

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AlgTop8: Polyhedra and Euler's formula

We investigate the five Platonic solids: tetrahedron, cube, octohedron, icosahedron and dodecahedron. Euler's formula relates the number of vertices, edges and faces. We give a proof using a triangulation argument and the flow down a sphere. This is the eighth lecture in this beginner's

From playlist Algebraic Topology: a beginner's course - N J Wildberger

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Visual Group Theory, Lecture 2.3: Symmetric and alternating groups

Visual Group Theory, Lecture 2.3: Symmetric and alternating groups In this lecture, we introduce the last two of our "5 families" of groups: (4) symmetric groups and (5) alternating groups. The symmetric group S_n is the group of all n! permutations of {1,...,n}. We see several different

From playlist Visual Group Theory

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Inkscape Logo Design: How to Make a Circle Logo Template | Curve Text | Create Pattern Fill

Inkscape step-by-step beginner, intermediate tutorial on how to create circle logo template. Follow along in this screen capture guide showing you how to curve text, wrap text around the bottom of a circle, create your own custom pattern fill and use Inkscape's render feature to generate a

From playlist Logo Design Tutorials

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Non-euclidean virtual reality

Try at http://h3.hypernom.com and http://h2xe.hypernom.com. Controls: wasd rotates, arrow keys move, numbers change decoration, c changes colours. Also works on smartphones - touch the screen to move forwards. If you have a Vive, you may be able to get this to work on Firefox - press v th

From playlist GPU shaders

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AlgTop16: Rational curvature of polytopes and the Euler number

We show that the total curvature of a polyhedron is equal to its Euler number. This only works with the rational formulation of curvature, using an analog of the turn angle suitable for the 2 dimensional sphere. This important modification to the theory is original with this lecture series

From playlist Algebraic Topology: a beginner's course - N J Wildberger

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Marjorie Wikler Senechal - Unwrapping a Gem - CoM Apr 2021

If the celebrated Scottish zoologist D’Arcy W. Thompson (1860 – 1948) could have met the near-legendary German astronomer Johannes Kepler (1571 – 1630), what would they talk about? Snowflakes, maybe? It is true that both men wrote about their hexagonal shapes. But they both wrote about Arc

From playlist Celebration of Mind 2021

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A Challenging Geometric Construction

Mathematics is patterns and logic, imagination and rigor. It is a way of seeing and a way of thinking. Math Mornings is a series of public lectures aimed at bringing the joy and variety of mathematics to students and their families. Speakers from Yale and elsewhere will talk about aspects

From playlist Math Mornings at Yale

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Seminar: Five-fold symmetry, Schiffler points and the twisted icosahedron

This is a seminar talk given at UNSW in the School of Mathematics and Statistics. It discusses joint work with Dr. Nguyen Le of San Francisco State University on a combination of projective geometry and triangle geometry, figuring five fold symmetry, dihedral orderings, a lovely distance r

From playlist MathSeminars

Related pages

Hexagon | Icosahedral symmetry | Alternation (geometry) | Rectified truncated tetrahedron | John Horton Conway | Rhombic enneacontahedron | Pentagon | Symmetrohedron | Harold Scott MacDonald Coxeter | Isosceles triangle | Truncation (geometry) | Rectified truncated dodecahedron | Convex polytope | Rectification (geometry) | Rectified truncated cube | Truncated icosahedron | Polyhedron | Pentakis dodecahedron | Rectified truncated octahedron | Regular Polytopes (book) | Near-miss Johnson solid | Conway polyhedron notation | Geometry