QUOTE(Elnendil @ Oct 8 2010, 10:53 AM)
"Are you explaining divisibility to me? I was clarifying that it's not something you have to prove, because it's basically the definition."
Yeah but it doesn't hurt to clarify.
Clarify what...?
QUOTE(Elnendil @ Oct 9 2010, 02:34 PM)
Last night when there were some quiet moments I skimmed through my Trigonometry book, since, well, lets say the Professor that taught me was hard to follow. Very very hard to follow. Example: A few days ago I wondered why sinx/cosx=tanx, and I worked it out and I thought it was neat. Then I realized thats in chapter 2 of a class I already took. Granted Calculus actually smooths these issues out with more applications you have to use, but I still have times where I have to check the double angle formulas etc.
Huh? To figure out why, you'd need to define them first. What were the definitions you used to derive them?
As a kid, using SohCahToa I basically did sin/cos = (o/h)/(a/h) = o/a = tan. But that's not really a proof because it assumes SohCahToa, and I didn't know what SohCahToa was defined by. (I also used it to remember sin^2+cos^2 = (o/h)^2 + (a/h)^2 = (o^2 + a^2) / h^2 = h^2/h^2 = 1)