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).
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
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
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
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
Joint work with Rick Rubenstein. Available from Shapeways at http://shpws.me/r1iO
From playlist 3D printing
Geodesic domes: http://shpws.me/qrM2 Geodesic spheres: http://shpws.me/qrM3
From playlist 3D printing
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
Platonic and Archimedean solids
Platonic solids: http://shpws.me/qPNS Archimedean solids: http://shpws.me/qPNV
From playlist 3D printing
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
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
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
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
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
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
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
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
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
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
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