Comment Re:Because so many more enter college these days? (Score 1) 841
He probably doesn't use those trig identities each day anyway. It's basic stuff, you'd think a math professor will be doing research that's slightly more involved than that! Heck, if your research involves lots of trig identities (somehow), you are dumb if you do it by hand, as you'd be wasting time with inevitable mistakes. If you need lots of trig identities done, you use a symbolic math package to do it for you. I'd think there's plenty of profs out there who do quite high level research and would pretty much suck at some of the undergraduate level stuff. I don't remember the trig identities, even if I could prove or derive every one of them in a couple of minutes.
That is exactly the point. If you are memorizing these identities then you are doing it wrong. It is actually much easier to learn to derive them, since they are all derived in essentially the same way. Memorizing a thousand identities just wastes your time.