I have a page I copied out of the back of my mathbook that has most of the common identities listed. You definitly need to write them down for referance. You begin to remember them after using them long enough.

]]>tan² x + 1 = sec² x

1 + cot² x = cosec² x

There's also the obvious sin x / cos x = tan x and the half and double angle formulae, but I can't remember them and I don't have the textbook with me.

]]>So far, I know that sin² x + cos² x = 1 and cos² x = 1 - sin² x. I skipped several math classes and headed straight for AP Calculus...Everything else is pretty easy, but I can't seem to get the trig down.

A list of all the pythagorean identites would be very much appreciated.

Thanks in advance.