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Prove each identity. 1.->  cos^2x-sin^2x=2cos^2x-1 identites include- ...

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sasuke24 | Student, Undergraduate | (Level 2) Honors

Posted December 8, 2012 at 10:38 PM via web

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Prove each identity. 1.->  cos^2x-sin^2x=2cos^2x-1 

identites include- 

cscx=1/sinx , secx=1/cosx , cotx=1/tanx , tanx=sinx/cosx , cotx=cosx/sinx , sin^2x+cos^2x=1

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lfryerda | High School Teacher | (Level 2) Educator

Posted December 9, 2012 at 12:18 AM (Answer #1)

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If you have more than one question you need to make separate posts.

In order to prove this identity, you need to start with one side, and then using existing identities, end up at the other side of the identity.

`LS=cos^2x-sin^2x`   use `sin^2x+cos^2x=1`

`=cos^2x-(1-cos^2x)`   remove brackets

`=cos^2x-1+cos^2x`  collect like terms



The identity has been proven.

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