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Prove trig identities

  1. Mar 11, 2013 #1
    1. The problem statement, all variables and given/known data
    Prove the following:

    tan2A=2tanA/1-tan^2A

    2. Relevant equations



    3. The attempt at a solution

    Took the right hand side:

    =2(sinA/cosA) / 1-(sin^2A/cos^2A)
    =2sinA/cosA /cos^2A-sin^2A/cos^2A
    =2sinA/cos2A /cosA/1

    Dont know what to do next?
     
  2. jcsd
  3. Mar 11, 2013 #2

    Dick

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    What's an identity for sin(2A)? And I hope 2sinA/cos2A /cosA/1 means (2sin(A))/(cos(2A)/cos(A)) what you've written is not at all clear.
     
    Last edited: Mar 11, 2013
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