I'm currently in first year calculus, and I'm having trouble remembering all my trig for use in derivatives. I have some stuff memorized, obviously soh cah toa, and the derivatives of the six trig functions. i.e. derivatives of sinx = cosx cosx = -sinx tan = sec^2(x) etc... but when using them in an equation there are other properties which I'm not sure of. For example: cos(0) = 1 (or something like that?) and sinx/x = 1. No where in my trig section does it point out these properties or explain them (I have,however, found proofs of sinx/x = 1 online), it seems to be required knowledge that the textbook assumes you know... but I don't. So what I'm asking is, does anyone know where I could look (possibly a webpage) where I could find these properties? Or is there a proper name I can check the appendix of my textbooks for that might explain these things for me.