Added by Chris M. Farkas on November 17, 1998 at 18:42:12:
(sin^2 x) + (cos^2 x) = 1
1 + (tan^2 x) = (sec^2 x)
1 + (cot^2 x) = (csc^2 x)
tan x = (sin x)/(cos x)
cot x = (cos x)/(sin x)
cot x = 1/(tan x)
sec x = 1/(cos x)
csc x = 1/(sin x)
sin (-x) = -sin x
cos (-x) = cos x
tan (-x) = -tan x