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Homework Help: Help with proofs

  1. Apr 23, 2005 #1
    I need help solving these 2 proofs:

    (sec^2x-1)/(sec^2x) = sin^2x
    I am not sure what direction to go in. I know the top of the left side could be changed into:
    tan^2x/sec^2x, but I don't know what to do after that.

    The second one I need help with is:

    cos^2x/(1+tan^2x) = cot^2x
    I simplified it into:
    cos^2x/sec^2x = cos^2x/sin^2x, but I don't know what to do after that. Can you help me get the next few steps of these problems? Thanks!
  2. jcsd
  3. Apr 23, 2005 #2


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    Actually, your already done....you just don't know it.

    remember that tanx=sinx/cosx? try that

    this one is done. again, remember that cotx=1/tanx, so what is cotx in terms of sin and cos?
  4. Apr 24, 2005 #3
    chase.....u seem to be a small boy just starting to learn math....am i right?????

    first problem....sec^2 x-1/sec^2 x=sin^2 x......
    ie.....tan^2 x/sec^2 x=RHS
    ie.....sin^2 x*cos^2 x/cos^2 x....that is equal to sin^2 x...isnt it?????/
    and the second problem u have given is wrong...there is some mistake in it......dont worry..trigonometry is easy......just try to create equations urselves....solve most of them using mind...then take ur pen......because u should be learning them like drinking water....so have them in ur fingertips.....
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