I’m not sure that I will make a habit of this. It’s been a while since I did a regular Reading the Comics post, looking for mathematics topics in syndicated newspaper comic strips. I thought I might dip my toes in those waters again. Since my Pi Day essay there’ve been only a few with anything much to say. One of them was a rerun I’ve discussed before, too, a **Bloom County** Sunday strip that did an elaborate calculation to conceal the number 1. I’ve written about that strip twice before, in May 2016 and then in October 2016, so that’s too well-explained to need revisiting.

As it happens two of the three strips remaining were repeats, though ones I don’t think I’ve addressed before here.

Bill Amend’s **FoxTrot Classics** for the 18th of March looks like a Pi Day strip. It’s not, though: it originally ran the 16th of March, 2001. We didn’t have Pi Day back then.

What Peter Fox is doing is drawing a unit circle — a circle of radius 1 — and dividing it into a couple common angles. Trigonometry students are expected to know the sines and cosines and tangents of a handful of angles. If they don’t know them, they can work these out from first principles. Draw a line from the center of the unit circle at an angle measured counterclockwise from the positive x-axis. Find where that line you’ve just drawn intersects the unit circle. The x-coordinate of that point has the same value as the cosine of that angle. The y-coordinate of that point has the same value as the sine of that angle. And for a handful of angles — the ones Peter marks off in the second panel — you can work them out by reason alone.

These angles we know as, like, 45 degrees or 120 degrees or 135 degrees. Peter writes them as or or , because these are radian measure rather than degree measure. It’s a different scale, one that’s more convenient for calculus. And for some ordinary uses too: an angle of (say) radians sweeps out an arc of length on the unit circle. You can see where that’s easier to keep straight than how long an arc of 135 degrees might be.

Drawing this circle is a good way to work out or remember sines and cosines for the angles you’re expected to know, which is why you’d get them on a trig test.

Scott Hilburn’s **The Argyle Sweater** for the 27th of March summons every humorist’s favorite piece of topology, the Möbius strip. Unfortunately the line work makes it look to me like Hilburn’s drawn a simple loop of a steak. Follow the white strip along the upper edge. Could be the restaurant does the best it can with a challenging presentation.

August Ferdinand Möbius by the way was an astronomer, working most of his career at the Observatory at Leipzig. (His work as a professor was not particularly successful; he was too poor a lecturer to keep students.) His father was a dancing teacher, and his mother was a descendant of Martin Luther, although I imagine she did other things too.

Rina Piccolo’s **Tina’s Groove** for the 2nd of April makes its first appearance in a Reading the Comics post in almost a decade. The strip ended in 2017 and only recently has Comics Kingdom started showing reprints. The strip is about the numerical coincidence between 3.14 of a thing and the digits of π. It originally ran at the end of March, 2007, which like the vintage **FoxTrot** reminds us how recent a thing Pi Day is to observe.

3.14 hours is three hours, 8.4 minutes, which implies that she clocked in at about 9:56.

And that’s this installment. All my Reading the Comics posts should be at this link. I don’t know when I’ll publish a next one, but it should be there, too. Thanks for reading.