Regular polyhedra | Deltahedra | Polyhedral stellation | Kepler–Poinsot polyhedra
In geometry, the great icosahedron is one of four Kepler–Poinsot polyhedra (nonconvex regular polyhedra), with Schläfli symbol {3,5⁄2} and Coxeter-Dynkin diagram of . It is composed of 20 intersecting triangular faces, having five triangles meeting at each vertex in a pentagrammic sequence. The great icosahedron can be constructed analogously to the pentagram, its two-dimensional analogue, via the extension of the (n–1)-dimensional simplex faces of the core n-polytope (equilateral triangles for the great icosahedron, and line segments for the pentagram) until the figure regains regular faces. The grand 600-cell can be seen as its four-dimensional analogue using the same process. (Wikipedia).
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
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
Canonical structures inside the Platonic solids III | Universal Hyperbolic Geometry 51
The dodecahedron is surely one of the truly great mathematical objects---revered by the ancient Greeks, Kepler, and many mathematicians since. Its symmetries are particularly rich, and in this video we look at how to see the five-fold and six-fold symmetries of this object via internal str
From playlist Universal Hyperbolic Geometry
Geodesic domes: http://shpws.me/qrM2 Geodesic spheres: http://shpws.me/qrM3
From playlist 3D printing
The remarkable Platonic solids I | Universal Hyperbolic Geometry 47 | NJ Wildberger
The Platonic solids have fascinated mankind for thousands of years. These regular solids embody some kind of fundamental symmetry and their analogues in the hyperbolic setting will open up a whole new domain of discourse. Here we give an introduction to these fascinating objects: the tetra
From playlist Universal Hyperbolic Geometry
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
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
The Music of the Icosahedron – Hilarie Orman
From playlist G4G11 Videos
Math Mornings at Yale: Asher Auel - Wallpaper, Platonic Solids, and Symmetry
The Platonic solids-the tetrahedron, cube, octahedron, dodecahedron, and icosahedron-are some of the most beautiful and symmetric geometrical objects in 3-dimensional space. Their mysteries started to be unraveled by the ancient Greeks and still fascinate us today. In 1872, the German geom
From playlist Math Mornings at Yale
Michael Tanoff - Son of O'Gara - G4G12 April 2016
Mathematical philately over the past half century
From playlist G4G12 Videos
Stanford Lecture: Don Knuth—"Hamiltonian Paths in Antiquity" (2016)
Computer Musings 2016 Donald Knuth's 23rd Annual Christmas Tree Lecture: "Hamiltonian Paths in Antiquity" Speaker: Donald Knuth About 1850, William Rowan Hamilton invented the Icosian Game, which involved finding a path that encounters all points of a network without retracing its steps.
From playlist Donald Knuth Lectures
Stanford Lecture: Don Knuth—"Hamiltonian Paths in Antiquity" (2016) (360 Degrees)
Computer Musings 2016 Donald Knuth's Christmas Tree Lecture (360 degrees): "Hamiltonian paths in Antiquity" Speaker: Donald Knuth About 1850, William Rowan Hamilton invented the Icosian Game, which involved finding a path that encounters all points of a network without retracing its step
From playlist Donald Knuth Lectures
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
Frank Wilczek - Why Do We Search for Symmetry?
Free access to Closer to Truth's library of 5,000 videos: http://bit.ly/376lkKN Symmetry is when things are the same around an axis. Turn it and it looks the same. A simple idea with profound implications for understanding the universe and for predicting how it works. Finding symmetries,
From playlist Closer To Truth - Frank Wilczek Interviews
Frank Wilczek - Why Do We Search for Symmetry?
What are the basic components of the cosmos? At the deepest levels of reality—the particles, fields and forces of the smallest slices of existence—how does the world work? Standard model of particle physics? Quantum theory? String theory? What are these theories, how do they work, and can
From playlist Closer To Truth - Frank Wilczek Interviews
Richard Esterle - Icosohedrons Almost 13 - G4G13 Apr 2018
Insights from my models and puzzles into the Icosahedron and sphere packing through the years. The Tetraball Puzzle and ICOSA 4 coloring.
From playlist G4G13 Videos
Domes top some of the world’s most well-known buildings. Here we countdown the largest domes that have ever been built. For more by The B1M subscribe now - http://ow.ly/GxW7y Read the full story on this video, including images and useful links, here: http://www.theb1m.com/video/the-world
From playlist The World's...
Group theory 27: The icosahedral group
This lecture is part of an online math course on group theory. The lecture is about a few examples of groups, in particular the icosahedral group. In it we see that the icosahedral group is the only simple group of order 60, and show that all larger alternating groups are simple.
From playlist Group theory