# verifying identities

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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 -

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 -

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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