78 posts tagged with geometry. (View popular tags)

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I'm looking for a textual version of *a*^{2} + *b*^{2} = *c*^{2} that is as old as possible, among all the Greek sources. [more inside]

posted by benito.strauss on May 12, 2014 - 5 answers

posted by benito.strauss on May 12, 2014 - 5 answers

Wizards of Hive,
Before I buy that 90" couch from a friend, how can I make sure I'll be able to get it up my L-shaped stairs? Sure, there are a lot of variables. But is there a tool or methodology for figuring this out ahead of time (presuming I know the depth and height of the couch too)? I don't think I have the cardboard to build a mockup.
This couch is 50 miles away and can't be returned. Thanks!

posted by baseballpajamas on Aug 21, 2013 - 14 answers

posted by baseballpajamas on Aug 21, 2013 - 14 answers

I'm drawing/painting a globe (in time lapse, so the sun appears to rise) and trying to figure out what shape, exactly, the longitude (not latitude) lines are when a globe is flattened into a circle (I know I can just trace them, but I've gotten curious). So, the outermost longitude lines are tangent to the circle, they are half-circles, and the centermost line is a straight line from pole to pole, it's the progressively flatter curves in between that I'm trying to figure out. Do they have a name? Are they catenaries? Are they the curves of progressively larger circles? How do I construct them (easily)? Example image: HERE

posted by sexyrobot on Jul 26, 2013 - 11 answers

posted by sexyrobot on Jul 26, 2013 - 11 answers

Here’s a simple computational geometry problem. I am trying to figure out the value at an point of two line segments based off of the values at both of one of the segment’s endpoints.
The problem is that I don’t exactly know the best way of going about finding the value at one of those points.
Here is a reference figure.
Given values
(X_C, YC) = F_C
(X_D, YD) = F_D
How can I calculate the value of F_E, where F_E = (X_E, Y_E), where E is the point on the segment CD, where CD intersects with the line AB?
(Extraneous details inside) [more inside]

posted by oceanjesse on Dec 5, 2012 - 10 answers

posted by oceanjesse on Dec 5, 2012 - 10 answers

Help me remember this old video series that used early computer/video animation to illustrate geometry/calculus concepts. [more inside]

posted by Wild_Eep on Aug 6, 2012 - 4 answers

posted by Wild_Eep on Aug 6, 2012 - 4 answers

Math is hard. Please help me with a slope-related problem. [more inside]

posted by anastasiav on Jul 22, 2012 - 11 answers

posted by anastasiav on Jul 22, 2012 - 11 answers

Are there an infinite number of 2D shapes? [more inside]

posted by mwachs on Jul 19, 2012 - 17 answers

posted by mwachs on Jul 19, 2012 - 17 answers

Calling geographers: has anyone applied the idea of topological prominence to population density? [more inside]

posted by miyabo on Apr 27, 2012 - 7 answers

posted by miyabo on Apr 27, 2012 - 7 answers

HTML5 canvas question: I'm trying to model a 2D grid in 3D space and it's not working right. Can you help? [more inside]

posted by The Winsome Parker Lewis on Apr 17, 2012 - 10 answers

posted by The Winsome Parker Lewis on Apr 17, 2012 - 10 answers

What is this geometric figure?
Is there a name for the figure inscribed in the circle here?

posted by vash on Apr 8, 2012 - 4 answers

posted by vash on Apr 8, 2012 - 4 answers

Looking for tips on implementing drag and drop that snaps to the nearest point on a polygon. [more inside]

posted by syzygy on Mar 29, 2012 - 13 answers

posted by syzygy on Mar 29, 2012 - 13 answers

Help me to learn math as an adult when I still despise the frustrating beast from my childhood! [more inside]

posted by DisreputableDog on Mar 24, 2012 - 20 answers

posted by DisreputableDog on Mar 24, 2012 - 20 answers

I'm looking for an awesome video/discussion topic that relates to street maps - something appropriate for a HS geometry course. [more inside]

posted by ch3cooh on Jan 3, 2012 - 7 answers

posted by ch3cooh on Jan 3, 2012 - 7 answers

Several years ago, I saw a website with a fun little flash or javascript applet thingy where you could build little tensegrity structure creatures, then have oscillating movements applied to the pieces, so that the structures would seem to "walk". I don't remember what it was called! From memory, one of the simpler structures looked sort of like this. What was it? Is it still online? [more inside]

posted by rivenwanderer on Jan 3, 2012 - 4 answers

posted by rivenwanderer on Jan 3, 2012 - 4 answers

I have forgotten basically all of math, and I want to learn it again from the ground up. [more inside]

posted by showbiz_liz on Oct 19, 2011 - 28 answers

posted by showbiz_liz on Oct 19, 2011 - 28 answers

Consider two rings that are intertwined. (These lie in 3-dimensional space, but when you draw it on paper it looks like a venn diagram.) In 3-dimensional space they cannot be unlinked. The questions is, if you had one more dimension, can you unlink them?

posted by gzimmer on Jul 15, 2011 - 14 answers

posted by gzimmer on Jul 15, 2011 - 14 answers

Geometry question -> Determine X and Y from distance along a straight line, or, how do I find the lengths of A and B if I know the length of C and the ratio of A to B in a right triangle? [more inside]

posted by syzygy on Jul 4, 2011 - 9 answers

posted by syzygy on Jul 4, 2011 - 9 answers

I'd like to be able to watch the Macy's fireworks from my dad's roof on the Upper West Side. How can I figure out if I'll be able to see them? I have some variables, heights, distances, and video... [more inside]

posted by thebazilist on Jul 1, 2011 - 7 answers

posted by thebazilist on Jul 1, 2011 - 7 answers

How does walking around on a hyperbolic plane differ from a euclidean one? [more inside]

posted by Hactar on May 20, 2011 - 9 answers

posted by Hactar on May 20, 2011 - 9 answers

Could someone help me with this geometry problem? Cylinder with a plane bisecting it at a 45° angle... [more inside]

posted by Tchad on May 2, 2011 - 19 answers

posted by Tchad on May 2, 2011 - 19 answers

I'm writing a graphics app where I'm generating a simple gear transmission system with a variable number of gears each with variable number of teeth and placed at random orbits around each other. I generate gears in succession, placing and rotating each with respect to its parent/driver gear before moving on to the next. The problem I'm having is how to determine the initial orientation of each subsequent gear such that its teeth are properly meshed with that of its driver. [more inside]

posted by Epsilon-minus semi moron on Oct 25, 2010 - 6 answers

posted by Epsilon-minus semi moron on Oct 25, 2010 - 6 answers

Given a set of points on a plane (or in a bounded region), how do I find the radii of circles centered at each point that provide the best covering? [more inside]

posted by Eamon on Oct 19, 2010 - 28 answers

posted by Eamon on Oct 19, 2010 - 28 answers

How should I colour each isocoles tetrahedron in a chain of 24 using three colours, so that when I fold up the chain into a rhombic dodecahedron each rhombic face is a single colour and is different to its neighbours? [more inside]

posted by Brentusfirmus on Sep 16, 2010 - 10 answers

posted by Brentusfirmus on Sep 16, 2010 - 10 answers

I want a flat, rectangular image that is a cylindrical map projection of the edges of a icosidodecahedron. How do I make one? [more inside]

posted by matt_arnold on Jun 26, 2010 - 10 answers

posted by matt_arnold on Jun 26, 2010 - 10 answers

I'm trying to find a website that teaches vector mathematics in lesson form. [more inside]

posted by giggleknickers on May 3, 2010 - 2 answers

posted by giggleknickers on May 3, 2010 - 2 answers

MathFilter: Is there a relationship between the number of dimensions in a Euclidean space and the number of regular tessellations of that space? [more inside]

posted by jedicus on May 2, 2010 - 10 answers

posted by jedicus on May 2, 2010 - 10 answers

Where can I find free geometry text diagram creating software? Even not so free software seems to not do what I want. I want to be able to draw simple plane geometry figures (e.g. right triangles) with markings (e.g. to indicate lines are perpendicular or angles are equal) and labels (e.g. of a line's length or the name of an angle) and such. [more inside]

posted by Obscure Reference on Apr 23, 2010 - 13 answers

posted by Obscure Reference on Apr 23, 2010 - 13 answers

Contemporary Geometry: does it exist? [more inside]

posted by Jason and Laszlo on Jan 18, 2010 - 14 answers

posted by Jason and Laszlo on Jan 18, 2010 - 14 answers

What is the graph or plot called which:
- is an equilateral triangle
- has three axes
- each axes is perpendicular to a side of the triangle? [more inside]

posted by Peter Petridish on Oct 28, 2009 - 10 answers

posted by Peter Petridish on Oct 28, 2009 - 10 answers

Geometry Wars Filter: Help configure Nyko Airflo PC game controller for Geometry Wars Retro Evolved (PC) [more inside]

posted by FusiveResonance on Sep 18, 2009 - 2 answers

posted by FusiveResonance on Sep 18, 2009 - 2 answers

Photoshop Question: is there a way to get a count of pixels contained within any (irregularly shaped) selection/layer? [more inside]

posted by unmake on Sep 10, 2009 - 2 answers

posted by unmake on Sep 10, 2009 - 2 answers

How can I estimate the time that a photo was taken? [more inside]

posted by zvs on Aug 5, 2009 - 11 answers

posted by zvs on Aug 5, 2009 - 11 answers

What software can I use to make a photo collage using non-rectangular photos? [more inside]

posted by soelo on Jun 9, 2009 - 3 answers

posted by soelo on Jun 9, 2009 - 3 answers

Is there an equation that defines the change in apparent size as a function of distance from the viewer? Basically, if I'm looking at a set of railroad tracks head on, if one plank is like 10 ft away, it appears to be one size. The same plank 20 ft away appears smaller. What is the relative size difference? Put another way, how big does a 1ft line appear to be at 10 ft, at 20 ft, etc.? [more inside]

posted by miasma on May 16, 2009 - 15 answers

posted by miasma on May 16, 2009 - 15 answers

I've got a polygon of *n* points. How can I simplify out noisy edges? [more inside]

posted by soma lkzx on Mar 31, 2009 - 12 answers

posted by soma lkzx on Mar 31, 2009 - 12 answers

Hi I'm trying to find a piece of art - a series of lights attached to wooden arms whose tips trace some sort of toroidal geometry. At high speeds the armature disappears and the lights form volumes as luminous wireframes, like synchronised mechanical sparklers. [more inside]

posted by doobiedoo on Mar 5, 2009 - 5 answers

posted by doobiedoo on Mar 5, 2009 - 5 answers

can you help me compute the area of a triangle on the sphere? [more inside]

posted by klanawa on Feb 4, 2009 - 20 answers

posted by klanawa on Feb 4, 2009 - 20 answers

posted by jjjjjjjijjjjjjj on Jan 9, 2009 - 34 answers

Math filter: How many equally sized rectangles will fit into a circle, and how should I arrange them in order to make the best-looking approximation? [more inside]

posted by brandnew on Aug 17, 2008 - 9 answers

posted by brandnew on Aug 17, 2008 - 9 answers

How can I tile a sphere using the minimum number of differently shaped units? I have a 3 meter diameter sphere and I need to tile it using units that are each about 400 square cm (ie like a 20 x 20cm square). The units must be flat (ie, not spherical triangles). [more inside]

posted by silence on Jun 2, 2008 - 14 answers

posted by silence on Jun 2, 2008 - 14 answers

How far would I need to travel from a tower 100 feet high before the sight of it would become obscured by the horizon? [more inside]

posted by grrlaction on May 4, 2008 - 20 answers

posted by grrlaction on May 4, 2008 - 20 answers

I read a book sometime in elementary school (early/mid 90's) that I've been trying to find. It had to do with geometry and math and platonic solids and origami (I believe there were several nods to Flatland). The plot had something about evil army men toys and a boy having a fever dream. I think the cover had a picture of the boy riding a manta ray. [more inside]

posted by rivenwanderer on Mar 31, 2008 - 3 answers

posted by rivenwanderer on Mar 31, 2008 - 3 answers

My geometry teacher in high school in 1984 showed us this puzzle. I was only half paying attention, but I believe the goal was to draw a line that intersected each segment only once. [more inside]

posted by mecran01 on Jan 6, 2008 - 15 answers

posted by mecran01 on Jan 6, 2008 - 15 answers

Does anyone teach a course in Synergetic Geometry in Los Angeles??? In the U.S.???? [more inside]

posted by goalyeehah on Aug 27, 2007 - 1 answer

posted by goalyeehah on Aug 27, 2007 - 1 answer

Help me with the math of two spheres colliding [more inside]

posted by RobotHero on Jun 10, 2007 - 8 answers

posted by RobotHero on Jun 10, 2007 - 8 answers

3D Trig question: I have a 2D square in 3D space (a Face). I know the positions of the four corner vertices in form x,y,z. How do I calculate the rotation in degrees (Euler angles) as relative from the center of the face?
I want to end up with degrees of rotations around x-axis,y-axis,z-axis. Bonus if you can write it in pseudocode.

posted by pooya on May 9, 2007 - 7 answers

posted by pooya on May 9, 2007 - 7 answers

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