What is wrong with this picture?

This image illustrating the Pythagorean Theorem was created by the artist Mel Bochner. It appears on the cover of the January 2009 issue of the College Mathematics Journal. What is wrong with it? For the answer, visit the 360 blog. Advertisements

What are p-adic numbers?

I am not a number theorist, but I’ve always had a distant fascination with p-adic numbers. I have a list of “neat math topics” that I want to write about on my blog, and the p-adic numbers are on that list. So I was happy to see an interesting article about them by Andrew Rich…

Measuring an angle with a ruler

In the September 2008 issue of the College Mathematics Journal Travis Kowalski presents an neat way to measure an angle using a ruler.  He attributes the discovery to a student of his, Tor Bertin. Given an acute angle (the technique can be modified for obtuse angles), measure off a distance on each ray.  Then measure…