Everything I learned in school and can't remember today is useless.
There goes most of history, math (I do remember some math but most of the school math is pointless), language & literature (I like reading, I just never liked the selection), physical education and lots of other subjects.
It's not that they aren't interesting per se, it's that school ruins them for you. By reading wikipedia for half an hour I understand more than from a month of a subject in school.
I could have better use for the time spent on this.
Your second example is practice--think of it as training the ALU in your brain.
In the first example, learning those trig relations is useful later for doing calculus and other things. You may forget them over time, but to have never been exposed to them would be a loss.
The answer that "Well, I can just Wikipedia them later!" assumes that you know what to look for later. This turns you from being a thinking person into a glorified cache for the internet. I'm not sure that's a good thing.
What if I don't want to train any TLAs?
The problem with trig relations is that school math makes a whole lot of grindingly huge excercises out of them; and then grade you by your ability to do the mental clownade.
I'm so not into this.
If you like reading, is it worthless for the authors who will write the books that you will read to have studied history, language and literature?
Or in other words, do you use/consume stuff that are the product of what you can't remember from school? And if so, does that make [edit] the knowledge behind them less useless?
No.
I know my native language pretty fine. I never liked literature they reach in schools. I don't remember anything from the history course in school, it was boring. I mean, they just can't make it interesting. Because it's not their (textbook authors) priority. So it tends to bore to death.
Everything I know about history is either from books I read by myself or from wikipedia/internet.
