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Homework Help: Proving Trigonometric Identities

  1. Aug 8, 2010 #1
    1. The problem statement, all variables and given/known data

    Prove (using the left side):

    sinΘ tanΘ = cosΘ sec^2Θ - cosΘ

    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Aug 8, 2010 #2

    HallsofIvy

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    Science Advisor

    [tex]sin(\theta)tan(\theta)= \frac{sin(\theta)}{cos(\theta)}tan(\theta)cos(\theta)= \tan^2(\theta)cos(\theta)[/tex]

    Now use the fact that [itex]tan^2(\theta)= sec^2(\theta)- 1[/itex].
     
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