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!

Limit value using definition of derivative

  1. Nov 1, 2011 #1
    1. The problem statement, all variables and given/known data
    I have encountered a limit that I wasn't really sure whether I was solving right, it's limit (a). I thought that I could find it considering a function f(x) (b) , find the derivative of that function and substitute x->1 so that I can find the value of the limit. Is this correct thinking???


    2. Relevant equations

    (a) lim(x->1) [ sin(x*pi/4) - sin(pi/4) ] / x-1

    (b) f(x) = sin(x *pi/4) and so f ' (x) = pi/4 cos(x* pi/4)


    3. The attempt at a solution
    That would mean that (a) = f ' (1) = pi/4 * (√2)/2 , right?
     
  2. jcsd
  3. Nov 1, 2011 #2

    lurflurf

    User Avatar
    Homework Helper

    yes that is right
     
  4. Nov 1, 2011 #3
    Ok, excellent, thanks!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook