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 on Jan 6, 2008 - 14 answers

Help me with the math of two spheres colliding [more inside]
posted on Jun 10, 2007 - 8 answers

How can I work out if a point x,y,z is contained by a cone ? [more inside]
posted on Jan 14, 2007 - 15 answers

Vector Geometry Filter: I'm working in matlab and need to transform a surface to match an arbitrary angle. I have the unit vector of the new normal (and the original normal is in the Z axis (0 0 1))...however i'm not sure how to rotate one normal to another (i know, i know, it sounds very simple really...) [more inside]
posted on Oct 23, 2006 - 5 answers

My room has an angled ceiling. I have measured its height at the highest and lowest points, and I have the dimensions of the room. Help me determine what height the ceiling is at a particular point on the floor, and where exactly the skylight is. [more inside]
posted on May 23, 2006 - 11 answers

Programming/geometry: in a Flash program (you don't need to know Flash to answer this), I'm trying to place rectangular images at random positions on the screen. There are already images on the screen. I need to make sure that the new, randomly-placed images don't obscure the images already there. [more inside]
posted on Sep 29, 2005 - 25 answers

Is there a specific name for a rectangle which, if you divide it in half, the two halves have the same proportions as the original rectangle? [more inside]
posted on Sep 27, 2005 - 12 answers

Remember the Spirograph? [more inside]
posted on Jul 11, 2005 - 13 answers

I have a circular patio table with four legs. The paving stones are uneven, so it has always been difficult to set the table in place so it doesn't wobble. I move it regularly, since the shadows from the trees change, and sometimes I want shade, other times sun. I used to mark small dots on the stones so I could set it down quickly. Then I discovered something very interesting--no matter where I put the table, if I simply rotate it around its center, I can very quickly find a steady configuration. But move it from place to place, and it takes all day. This is like the four color map theorem. It works every time, but I haven't figured out why. It might even be tricky to put this into a mathematical format. The table doesn't need to be level, and all four legs needn't be the same height or "at" the same height. The table just can't wobble. Go geeks.
posted on Mar 10, 2005 - 10 answers

What do you call those three-dimensional geometric novelties, consisting of eight cubes, joined to each other at one edge to form one large cube, whose pieces can be flipped around to display different images on the exterior of the large cube? What is the history of this delightful object? What are the geometric priniciples behind it?
posted on Jan 20, 2005 - 15 answers

I read Edwin A. Abbott's Flatland this weekend and really enjoyed its fiction and speculative geometry/mathematics. I guess the logical next step would be to read the unofficial sequel, Flatterland, but can any of you recommend other books that similarly twist math and fiction, or just books that explain mathematical concepts or theories to laymen such as myself in ways that are entertaining to read?
posted on Jan 3, 2005 - 28 answers