Posted by Dizzytrig on Tuesday, July 22, 2008 at 11:09am.
how do you veriy
tan x + Cot y
 = tan y + cot x
1tan x cot y
sin^4x + cos^4x = 1 2cos^2x + 2cos^4

verifying identities  Damon, Tuesday, July 22, 2008 at 4:57pm
I get on the right:
sin y / cos y + cos x / sin x
(sin x sin y + cos x cos y) / sin x cos y
sin x sin y/cos x + 1 cos y

sin x cos y/cos x
tan x sin y + cos y

tan x cos y
tan x sin y/sin y + cos y/sin y

tan x cos y/sin y
tan x + cot y

tan x cot y 
verifying identities  Damon, Tuesday, July 22, 2008 at 5:00pm
sin^4x + cos^4x = 1 2cos^2x + 2cos^4 this is not complete, assume you mean
2 cos^4 x at the end
sin^4 x = sin^2 x * sin^2 x
=(1  cos^2 x)(1  cos^2 x)
= well I guess that gives it away