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Limit with trigonometric functions

  1. Nov 23, 2009 #1
    1. The problem statement, all variables and given/known data

    True or false?

    lim Tanx/(1-Cosx) = lim Sec2x/Sinx = Infinity

    (limits are as x approaches [tex]\pi[/tex] from the left)

    3. The attempt at a solution

    I tried just plugging [tex]\pi[/tex] into x in the first limit, and I ended up getting 0/2, which exists but is just 0. So I said false. Am I simplifying it too much? because what I did seems to make sense but it looks like that's not what they wanted me to do.
    Last edited: Nov 23, 2009
  2. jcsd
  3. Nov 23, 2009 #2
    Re: limit

    Isn't it just 0/2=0?
  4. Nov 24, 2009 #3


    Staff: Mentor

    Re: limit

    The original limit was neither of the indeterminate forms [0/0] or [infinity/infinity], so L'Hopital's Rule doesn't apply here. Your first approach was correct.
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