**tl;dr:** Notetakermakers, homework, and study guides for trig sum/difference/double/half angles, trig identities, and solving trig equations. Part of my ongoing series of posting all of my files; see more and FAQs on this page. Plus I tell you about an awesome book at the end!

Yes, I love trig. I love that I there’s always new ways to think about and teach it. I love that it’s so elegant. And I love that it’s one of those topics that looks scary and is scary and new but eventually most kids get it and feel so smart about it.

Now, check out the middle box of the “three fraction hints” above. If it’s the first time you’ve seen this multiply-by-the-common-denominator-of-the-small-denominators, then be sure to read this post about it. It’s totally awesome and is so handy in Precal and Calculus!

Now, don’t worry, we don’t do all of those in identities in one day! We do the first six together:

Then I have them work on the rest of the first column for homework with the rule: if you’ve been on a problem for more than 5 minutes without getting anywhere, stop and move on. Since I teach honors, I know some of them would get trapped in a problem for 20 minutes and then just get frustrated with the whole thing. Then we work on the others in class on group whiteboards for a day, and finish them up whenever we have a few minutes throughout the week.

and say, “we do *not* have the same sign.” Although, confession: I have no idea how the story is supposed to help memorize the tangent sum/difference formula–please let me in on the secret if you know it! Another confession: Crazy Stupid Love is one of my favorite movies of all time.

FOCUS! Back to sum and difference:

File here. We also decided this year not to do the problems like 7 and 8 so I will allow you to skip those as well. You’re welcome.

File here. If you do skip 7 and 8, also skip 12, 13, 18-20 on the homework.

Some double/half angles:

File here. Fun tip: have them derive the double angle formula of sin and cos from the sum formulas and then everybody gets to feel smart.

File here. Now’s a good time to consolidate all our knowledge:

File here. (omit #19 if you’ve been omitting stuff) And then begin solving trig equations!

And then some quadratic and mixed equations!

It’s only one section, but worthy of its own study guide and test.

File here. There’s even a couple showme videos for the study guide: #1-9 and #10-16

**My Thing**

My thing this week is Simon vs. The Homo Sapiens Agenda. I read about 50 pages of it the night before last, then spent all afternoon yesterday finishing it because I HAD TO KNOW WHAT WAS GOING TO HAPPEN TELL ME TELL ME TELL ME. And it’s obvious that the author works with teenagers because the dialogue is spot-on. And they’re normal teenagers doing normal teenager-y things which is a rarity in YA. And it’s just a nice pleasant story where no one dies, not even the dog. 🙂

## Anna Vance

June 21, 2017 at 7:42 am

Just now caught that you didn’t get how the tangent sum and diff formula worked because I read it like 5 times trying to figure it out and still couldn’t #whew #ingoodcompany

## Meg Craig

July 12, 2017 at 3:17 pm

The good news is I’ve been told the tangent formulas don’t come up a lot in Calculus. 🙂