Girls’ Angle Bulletin, Volume 6, Number 5

In Volume 6, Number 5, we present an interview with Kirsten Wickelgren, a fellow at Harvard University who will be moving to Georgia Tech in the fall. The mathematics Dr. Wickelgren mentions is mostly post-high school level. For one of the topics she mentioned, we tried to bridge the gap by supplementing with a Summer Fun problem set that dips its feet into number systems beyond the integers.

Also featured is an article on Euler’s totient function by Lola Thompson, a postdoc at the University of Georgia who will be moving to Oberlin in the fall as an assistant professor of mathematics. Much content in the Bulletin arises out of the interests of our current members and subscribers, and this article is a perfect example. We hope you enjoy Dr. Thompson’s lucid explanation of two important facts about the totient function, which counts the number of numbers between 1 and n, inclusive, that are relatively prime to n. This article was supported in part by a generous grant from MathWorks.

Coach Barb’s Fraction Satisfaction has turned into a saga featuring the inimitable 3/7 and “you.” In this issue, the two tie up some loose ends about an algorithm that produces Egyptian fractions from the previous issue.

The best way to learn math is to do math, and the June issue marks the traditional appearance of the Summer Fun problem sets. Shravas Rao returns with a neatly gradated series of problems on Vieta’s formulas. If you don’t know about Vieta’s formulas, you’ll learn them well by doing his problem set. Robert Donley also returns, capping his series on Fermat’s little theorem with a nifty problem set where you will prove the Gauss-Wilson theorem. Girls’ Angle advisor, now Princeton University graduate student, Lauren McGough contributes a really fun and interesting problem set about signaling.

The first Summer Fun problem set relates to the cover and gives you the opportunity to learn about  perspective drawing by drawing. The cover shows a  stereo pair of the view of Boston from Robbins Farm Park in Arlington. Perspective drawings are made for a specific location of the viewing eye.  Since we have two eyes, the views we perceive of the 3D world around us is slightly different in each eye. If the eyes are fed different views that are consistent with a 3D world, the brain will get a 3D illusion. Stereo pairs present two such views and to get the illusion, you have to aim your eyes so that one eye receives one of the images while the other eye receives the other image. This in turn relates to parallax, which is exploited in Math In Your World wherein it is explained how to turn yourself into a walking distance estimation machine.

Finally, a reminder: when you subscribe to the Girls’ Angle Bulletin, you’re not just getting a subscription to a magazine. You are also gaining access to the Girls’ Angle mentors, and subscribers and members are urged to write in with your questions and solutions to the Summer Fun problem sets or anything else in the Bulletin or having to do with mathematics in general. We will respond. We want you to get active and do mathematics. Parts of the Bulletin are written to induce you to wonder and respond with more questions. Don’t let those questions fade away and become forgotten. Send them to us!

We continue to encourage people to subscribe to our print version, so we have removed some content from the electronic version.  Subscriptions are a great way to support Girls’ Angle while getting something concrete back in return.  We hope you subscribe!