## Girls’ Angle Bulletin, Volume 8, Number 1

This time, we’re leaving it up to readers to guess what our latest cover represents.

This past summer, Girls’ Angle program assistant Margo Dawes traveled to New York City to interview Cathleen Morawetz, Professor Emerita at the Courant Institute of Mathematical Science at New York University.

Last year, Professor Jennifer Roberts, the Elizabeth Cary Agassiz Professor of the Humanities at Harvard University, wrote an essay for Harvard Magazine about “creating opportunities for students to engage in deceleration, patience, and immersive attention.” Inspired by that essay, and recognizing that this could be a valuable exercise in mathematics as well, we attempt to give you such opportunities in mathematics with our new column, Meditate to the Math.  Our first installment features the 9-point circle. Instead of reading about the 9-point circle, we encourage readers to find a comfortable, quiet place, and contemplate a geometric figure. We hope this will be a way to take part in the process of mathematical discovery.

Next, follow Emily and Jasmine as they contemplate 5-pointed stars. If any of our members or subscribers have an exciting story of mathematical discovery of their own, we welcome you to tell us about it!

This issue’s Learn by Doing addresses quadratic residues. Last Summer’s batch of Summer Fun Problem sets included one on quadratic reciprocity by Cailan Li.  But before quadratic reciprocity, there are lots of things to say about quadratic residues.  We explore some of those neat properties here.

Last issue, Anna made a neat discovery about stereographic projection and paraboloids of revolution. As often happens with mathematical theorems, the first proof is messy and then spiffier proofs are found later. In this issue’s Anna’s Math Journal, Anna finds a much nicer proof and then applies the result to describe a few more observations about paraboloids of revolution.

While contemplating paraboloids of revolution, Anna also came upon a way to understand the radical axis of two circles. This observation seemed more convenient to write an article on because she came to this understanding without writing anything down. She explains in Seeing the Radical Axis. Lightning Factorial supplements her article by briefly defining the radical axis for readers not yet familiar with the concept.

A few weeks ago at the Girls’ Angle club, some members helped to simplify Lunga Lee’s excessively long descriptions of various functions. You can try your hand at this in Function Madness.

Also inside are another installment of Math In Your World, some exercises about real algebraic varieties (to follow-up on Dr. Zamaere’s introduction of them in her interview in the previous issue), and some notes from the club, which include a summary of Emily Pittore’s recent visit.  Emily is a robotic vision engineer from iRobot, the maker of the Roomba vacuum cleaner.

We hope you enjoy it!

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.  We urge all subscribers and members to write us with your math questions 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!