I always thought sohcahtoa itself was quite memorable. Sounds like a war cry!

We made this up in school: "saya tak hensem, kalau saya hensem, tentu Tipah suka" [opposite = tentang, adjacent = sebelah, cos = kos]

Translation: I'm not handsome, if I were handsome, Tipah (our principal) would like me"

25 years ago and I still remember it clearly. Also it was middle school education on how to solve problems in a different space; this one solving math in a second language space lol

In my school, it was "Some Old Hippie Caught Another Hippie Tripping On Acid," which succeeded in being quite memorable for me. In retrospect it seems a bit wild compared to some of the examples here, especially considering it was taught at a public school in the US deep south!

I learned it as: Some old hags, can't always hide, their old age.

I guess this is the version we use in Australia.

Sex On Holidays Can Advance Happiness To Outrageous Amplitudes. Not suitable for a high school class, though.

For us it was "Some officers have curly auburn hair 'til old age". Never seemed like a good mnemonic given that you have to shorten "until" to make it work and none of us had any idea what "auburn" was, but I still remember it 20 years later so...

No. Just "Sohcahtoa" was enough. Didn't need to create a backronym for it.

And the quadratic equation...yeah, I don't remember that one.

Sorry, what are all these mnemonics for? I can't imagine what you are trying to remember with these, as we never introduced such mnemonics in school.

In the UK it was “Attack Henry Cooper, outside his shop, on a Tuesday” no idea why the random violence but I never forgot it

some old hippie caught another hippie tripping on acid

If you know your trig well enough, you can derive the identities.

For example, knowing that cosine and sine are the exact same wave, just 90 degrees out of phase, it's trivial to know that sin(angle) = cos(angle + 90)

cos(a)^2 + sin(a)^2 = 1 is easy to show, too. If you use a=0, it's trivial. But try using 45 degrees. It turns into (sqrt(2)/2)^2 + (sqrt(2)/2)^2 which simplifies to 0.5 + 0.5 = 1.

Many of the others can be derived by just manipulating the Law of Sines or Law of Cosines. Fun fact: The Pythagorean Theorem is actually just a special case of the Law of Cosines:

c^2 = a^2 + b^2 - 2*a*b*cos(C)

Recall that in the Law of Cosines as I've written it, the lowercase letters are the sides, and the large C is the angle opposite that side. So if you choose your hypotenuse to be c, then the opposite angle, C, is 90 degrees. cos(90) is 0, so that whole last term gets cancelled out and you're left with the equation known as the Pythagorean Theorem.

I really wasn't kidding when I said I enjoyed trig.