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Simplifying the Trigonometric Expression Question

  1. Apr 19, 2009 #1
    1. The problem statement, all variables and given/known data

    cosx/(secx+tanx)



    3. The attempt at a solution

    So far I have this:

    =cosx/(1/cosx + sinx/cosx)
    =cosx/(sinx + 1/cosx)
    =cos2x/sinx + 1

    From there I don't know what to do. I've messed around with it for a while but don't seem to get anywhere.

    Any help is appreciated.
     
    Last edited: Apr 19, 2009
  2. jcsd
  3. Apr 19, 2009 #2
    Your last denominator is incorrect. It should be sinx + 1.
     
  4. Apr 19, 2009 #3
    Yeah you're right, thanks for pointing it out. Fixed now.
     
  5. Apr 19, 2009 #4
    cos2 x/(1 + sin x)
    (Let's keep the order of 1 and sin x.)

    Here's a hint: do you know of an identity that has a sin x (or a multiple or a power thereof) and a cos x (as before) in it?


    01
     
  6. Apr 20, 2009 #5
    Ahhh, I think I got it.

    1-sin2 x/1+sin x

    (1-sin x)(1+sin x)/1+sin x

    1-sin x!

    Right?
     
  7. Apr 20, 2009 #6
    Indeed that is correct!


    01
     
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