Posted by **Dizzytrig** on Tuesday, July 22, 2008 at 11:09am.

how do you veriy

tan x + Cot y

-------------- = tan y + cot x

1-tan 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

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