Current Events > When are you supposed to learn all those trig identities?

(+) Yeah! (+)

In algebra they barely talk about it

Then you take precalculus and it's just mentioned in passing (oh btw yeah there's some trig identities, but don't worry about it)

Then you go through differential calculus and it's meh, just remember some of the derivatives of inverse trig functions and it's ok

Then you get to integral, and it's like "omigod wtf you should've memorized all this shit years ago obi wan!"

Like... when?
---

You don't memorize. You keep a cheat sheet of identities in your butt.
---

Bruh I still haven't memorized them shits and I graduated with a Math degree last year
---

Just know the definitions and memorize sin squared x + cos squared x = 1 and derive the rest.
---

destrian522 posted...

Just know the definitions and memorize sin squared x + cos squared x = 1 and derive the rest.

I... don't think that's quite enough when you get to trig substitution. You really need to have everything memorized

No time in an exam to start deriving stuff
---

Thats all I did when I went through it. We used calc all day every day in my major.
---

Oh I forgot a useful one actually. I remember Eulers formula e^(ix) = cosx + isinx since its an easy way to derive angle addition and thus double angle trig formulas without geometry.
---

What's the point of learning it? It's useless for real life...
---

Never understood why you have to memorize formulas, it is not as if in real life you wont be able to google.
---

destrian522 posted...

Oh I forgot a useful one actually. I remember Eulers formula e^(ix) = cosx + isinx since its an easy way to derive angle addition and thus double angle trig formulas without geometry.

Yeah, but that's not something that's on the curriculum by the time you get to cal 2

Maybe it should be

When I did precalculus we didn't even touch on real and imaginary numbers, i just learned it by myself from a book
---

Yeah Im pretty sure I learned that trick after calc, but its still useful and easy to understand.
---