## Girls’ Angle Bulletin, Volume 9, Number 3

Volume 9, Number 3 begins with the concluding half of an interview with French mathematician Alice Guionnet. Prof. Guionnet is a professor of mathematics at MIT and an expert on random matrices.

The cover features an illustration by Julia Zimmerman for a fictional math story entitled The Mountain Clock.  The Mountain Clock tells the story of an ancient King who decreed a 32-hour day.

Katherine Cliff, a graduate teaching fellow at the University of Colorado, Colorado Springs, contributes this issue’s Math In Your World.  She brings the rational world of mathematics to the computation of probabilities for the Powerball lottery. If you work through this installment, you’ll be able to compute lottery probabilities and the value of a lottery ticket from scratch.

Anna continues her investigation of irreducible polynomials over the finite field with 2 elements. In this installment, she formulates 2 conjectures, works out implications of them, and proves one of them. Anna’s entire investigation traces back to an exercise suggested by Prof. Judy Walker in her interview from Volume 8, Number 6. Can you prove the conjecture she doesn’t prove?

Emily and Jasmine continue their quest for “nice” triangles. This time, they explore integer-sided triangles with no conditions at all on their angles. They determine the number of such triangles that have 2 given side lengths and begin to study the question of how many integer-sided triangles there are of a given perimeter.

In this issue’s Learn By Doing, you can try your hand at coming up with counterexamples. There are few things that so decisively prove a conjecture wrong than coming up with a counterexample!

There’s a lot more inside and 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!