#geometry

0x10f/kalle/qalle0x10f@tech.lgbt
2025-12-16

A coincidence in geometry:
Take a regular dodecahedron (yellow) and a regular octagon (blue), both with edge length 1. When they are concentric, some of the octagon's vertices seem to coincide with the centres of the dodecahedron's edges (see black circle).
But actually the dodecahedron's midradius is (3+√5)/4 or ~1.309, while the octagon's circumradius is just 1/√(2−√2) or ~1.307.

#geometry

screenshot from OpenSCAD: a yellow regular dodecahedron (12 pentagonal faces) and a blue regular octagon, both with the same edge length; the dodecahedron and the octagon are concentric and one of the octagon's vertices seems to lie at the centre of one of the dodecahedron's edges
Elliot Shankclonezone
2025-12-16

“A New Way to Look at Möbius Strips”

Nothing new in terms of results, even the ones that I knew as a kid, but a nice visualization that clarifies why things work out the way that they do.

youtube.com/watch?v=izIKV98Awnw

2025-12-15

Advent of Tilings - Day 16.2

The gluing rules and unfolded tiles.

t₂²
(f₁f₂)⁸
(f₁t₁t₁)³

#math #geometry #3d #combinatorics #tiling #AdventOfTilings

2025-12-15

Advent of Tilings - Day 16.1

Light enough for the mid-tree branches. Another best effort immersion of an intricate finite surface tiling of genus 169 that is made up of 1344 tiles.

#math #geometry #3d #combinatorics #tiling #AdventOfTilings

The Kid Should See This 🌈🪐✨tksst@fediscience.org
2025-12-15

🎁📐 @stecks demonstrates the logical approach to wrapping oddly shaped #presents. Her mathematical techniques work for cylinders, triangular prisms, and even squidgy-shaped #gifts through careful measuring and thoughtful folding.

👉 Learn more: thekidshouldseethis.com/post/m

#diy #holidays #howto #math #maths #geometry #stem #tksst #video

Hands demonstrating mathematical gift wrapping technique on rectangular present with colorful holiday pattern paper.
Dyalogdyalog
2025-12-15

2014-01: Write a function that takes the length of the legs of a triangle as its left argument, and the length of the hypotenuse as its right argument, and returns 1 if the triangle is a right triangle, 0 otherwise (see apl.quest/2014/1/ to test your solution and view ours).

0x10f/kalle/qalle0x10f@tech.lgbt
2025-12-15

Here's a "cheat sheet" for geometry. If you come across a number you don't recognise, e.g. 0.866025404, you can look up the number and see its exact value may be √(3)/2. If so, it's either the height of a triangle, inradius of a hexagon, circumradius of a cube or midradius of a cuboctahedron. (All the polygons and polyhedra are assumed to be regular and have edges of length 1.)
qalle.neocities.org/geometryma

#geometry

Sci-books.comscibooks
2025-12-15

Schwarz's Lemma from a Differential Geometric Viewpoint (Iisc Lecture Notes) by Kang-Tae Kim (PDF)
Author: Kang-Tae Kim
File Type: PDF
Download at sci-books.com/schwarzs-lemma-f
, -TaeKim

2025-12-15

Advent of Tilings - Day 15.2

The unfolded hexagonal tile in the Poincaré plane with zoom in.

Gluing rules are
t₂²
(f₁f₂f₁f₂f₁t₁)²

#math #geometry #3d #combinatorics #tiling #AdventOfTilings

2025-12-15

Advent of Tilings - Day 15.1

The growth of this genus 49 bauble made up of 384 tiles runs through several wonderfully twisted starry constellations before it finally closes up.

Below the growth steps starting from the initial hexagon to the final best effort immersion.

#math #geometry #3d #combinatorics #tiling #AdventOfTilings

2025-12-14

AlmostMatched

Video: youtube.com/watch?v=26e3_wmg06

Blogpost: blog.illestpreacha.com/wcccalm

#pixelation #glitchy #Livecoding #animation #WCCC #WCCChallenge #Almost #sounddesign

For this week's Creative Code challenge by @sableraph : “Almost”, AlmostMatched coded in #HydraVideoSynth & #SonicPi with the sketch being layered in a near Symmetrical way.

#poem

Almost
Nearly & Barely
On the Symmetrical Coast
Attempted to be on the even Post
Nearly & Barely
Almost

#creativecoding #coding
#newmedia #scifi #flowstate
#geometricart #geometry

2025-12-14
An Xover0 original gold-plated steel bangle suspended from a tree stump.
2025-12-13

Advent of Tilings - Day 14

A Genus 31 surface tiling needing 240 tiles to form, shown again grown ring by ring around the central tile.

The growth of the group elements
1 + 9 + 30 + 51 + 71 + 51 + 24 + 3 ‎ = 240

The looping relators (gluing rules)
t₂⁶
(f₁t₁)²
(t₂⁻¹t₁)³

#math #geometry #3d #combinatorics #tiling #AdventOfTilings

ƧƿѦςɛ♏ѦਹѤʞspacemagick
2025-12-13

@mf_magazine
LOL I've always done boxes that way - isn't it obvious?

Erik Kellyerk@gram.social
2025-12-13
📍 Lancaster, PA
🗓️ June 16, 2015
📷 Panasonic DMC-ZS40, 24mm equivalent, f3.3, 1/400th, ISO 100

#photography #glass #geometry #vintagecamera #vintagedigital #vintagedigitalcamera
The image shows a close-up view through a faceted glass object with a textured pattern creating a kaleidoscope-like effect. The glass is intricately designed with diamond-shaped cuts and star patterns, which distort and reflect the surrounding environment. Through the glass, a suburban street scene is visible, including parts of houses and greenery, but all appear warped and repeated owing to the glass texture. The central part of the image acts like a lens, presenting the scene in a more focused and less distorted manner.
Sci-books.comscibooks
2025-12-13

A Second Course in Mathematical Analysis (Cambridge Mathematical Library) by J. C. Burkill (PDF)
Author: J. C. Burkill
File Type: PDF
Download at sci-books.com/a-second-course-
, .C.Burkill

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