Results 1 to 2 of 2

Thread: bit of help needed on cos-1 differentiation

  1. March 1st 2009, 02:47 PM #1
    alpharebel10
    alpharebel10 is offline
    Newbie
    Joined
    Jan 2009
    Posts
    17

    bit of help needed on cos-1 differentiation

    find dy/dx when x=2 if
    y=cos-1 (x)
    i understand that
    -1 du
    squrt 1-u^2 dx
    but now i will get a negative number at the bottom and i cant get a square root of a negative number thank you 4 your time
    Follow Math Help Forum on Facebook and Google+
  2. March 1st 2009, 03:17 PM #2
    skeeter
    skeeter is offline
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,625
    Thanks
    425
    x = 2 is not in the domain of the inverse trig function y = \cos^{-1}{x}.
    the domain is -1 \leq x \leq 1


    you sure it isn't ...

    y = (\cos{x})^{-1} = \frac{1}{\cos{x}} = \sec{x} ?
    Follow Math Help Forum on Facebook and Google+
« The Sandwich Theorem | Second derivative test to find local min and max »

Similar Math Help Forum Discussions

  1. Basic Differentiation help needed...
    Posted in the Calculus Forum
    Replies: 3
    Last Post: August 3rd 2009, 06:40 AM
  2. Clarification with differentiation needed
    Posted in the Calculus Forum
    Replies: 1
    Last Post: November 8th 2008, 12:48 AM
  3. Help Needed !! Exponential Differentiation
    Posted in the Calculus Forum
    Replies: 5
    Last Post: July 18th 2008, 04:40 AM
  4. Numerical Differentiation help needed.
    Posted in the Calculus Forum
    Replies: 0
    Last Post: November 20th 2007, 01:38 AM
  5. homework help needed with differentiation
    Posted in the Calculus Forum
    Replies: 2
    Last Post: September 17th 2007, 06:49 PM

Search Tags


/mathhelpforum @mathhelpforum