1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Basic Limit Question

  1. Sep 3, 2011 #1
    I'm stuck on this one problem:
    lim (x=>0) cos^2x-1/x^2

    I know the answer is -1, however I'm having trouble getting there.

    Can anyone help me with this? I know cos^2x-1 is also -sin^2x and I'm having trouble with getting rid of the denominator. Thanks!
  2. jcsd
  3. Sep 3, 2011 #2
    So you know the following limit??

    [tex]\lim_{x\rightarrow 0}{\frac{\sin(x)}{x}}[/tex]


    If you don't know it, then you can calculate it with L'Hopitals rule. This limit will help you with the limit in the OP...
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook