1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    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!

Ok, Limit problem

  1. May 16, 2008 #1
    Ok, the problem is find the limit of x/sqrt(1-cosx) as x approaches 0 from the negative side.

    First I tried simply applying l'hopital's rule to see what would happen, and it didn't work.

    Next I tried rationalizing it by multiplying the numerator and denominator by sqrt(1+cosx), then using a trig identity (1-(cosx)^2=(sinx)^2 to get sqrt((sinx)^2) or simply sinx. Then I applied l'hopital's rule and ended up with a big mess that still ended up with 0/0.

    Did I miss something or do something incorrectly?
  2. jcsd
  3. May 16, 2008 #2


    User Avatar

    1 - cos(x) = 2sin^2(x/2)

    x/sqrt(1-cos(x)) = x/sqrt(2)sin(x/2)

    Using L'Hopitals on this does not lead to 0/0.
  4. May 16, 2008 #3
    So I was missing something, thanks.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Ok, Limit problem
  1. Is this ok? (Replies: 2)

  2. Limit problem (Replies: 4)

  3. Limit problem (Replies: 14)

  4. Limits problem (Replies: 4)