## Nice surprise

I was just informed that my blog was selected as one of the 50 Best Blogs for Math Majors [update: broken link]. I’m honored to be included with such a great list of math blogs.

## Topological maps or topographic maps?

While surfing the web the other day I read an article in which the author refers to a “topological map.” I think it is safe to say that he meant to write “topographic map.” This is an error I’ve seen many times before. A topographic map is a map of a region that shows changes…

## John D. Cook’s daily Twitter tips

One of the most prolific and interesting math bloggers and Twitters, John D. Cook (his blog is The Endeavor and he is @JohnDCook on Twitter) has been using Twitter in a very interesting way. In addition to his personal account, he has set up more than half a dozen daily Twitter messages on a variety of…

## Mathematical cousins and collaboration numbers

A couple days ago Michael Lugo at God Plays Dice shared a link to a mathematical relationships search. Enter the names of two people with PhDs in mathematics and it will spit out their academic relationship. For example, my advisor, John Franks, is my academic father and my good friend and collaborator Jim Wiseman is my academic…

## An Euler line geogebra applet

Lately I’ve been thinking a lot about Euler and his many contributions to mathematics. So, just for fun I decided to make a Geogeba applet showing the “Euler Line.” In 1763 Euler proved that three different centers of a triangle—the centroid, the orthocenter, and the circumcenter—are collinear. This line is called the Euler line. The centroid…

## Everyday geometry: hat size

I don’t wear hats very often. Occasionally I wear a baseball hat. Twice a year I wear the hat that accompanies my academic regalia. If you need to buy a hat, the first thing you need to know is your hat size. If you Google “hat size” then you can find many charts that match…