Results 1 to 4 of 4

Math Help - Laplace transform

  1. #1
    Member
    Joined
    Sep 2009
    Posts
    82

    Laplace transform

    cos(3t-1) I need to find the laplace transform of this.

    As given, I cannot just use the table of given identities. I think i need to use some trig function to seperate the cosine, but I cannot seem to find anything that seems to help....

    Is there anyway to seperate this into something a little easier?
    Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by snaes View Post
    cos(3t-1) I need to find the laplace transform of this.

    As given, I cannot just use the table of given identities. I think i need to use some trig function to seperate the cosine, but I cannot seem to find anything that seems to help....

    Is there anyway to seperate this into something a little easier?
    Thanks!
    Use 2.16(b) from here: Table of Laplace Transforms

    Note that \cos (3t - 1) = \sin \left(\frac{\pi}{2} - [3t - 1]\right) = - \sin \left(3t - 1 - \frac{\pi}{2}\right).

    (Or just do it from first principles by calculatiing the integral).
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Aug 2009
    From
    Mumbai
    Posts
    83
    \cos(3t-1) = \cos(1)\cos(3t)+\sin(1)\sin(3t)

    Therefore F(s) = \cos(1)L(\cos(3t))+\sin(1)L(\sin(3t))
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member
    Joined
    Sep 2009
    Posts
    82
    trig identities....they'll get you. Thanks
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Laplace transform and Fourier transform what is the different?
    Posted in the Advanced Applied Math Forum
    Replies: 8
    Last Post: December 29th 2010, 11:51 PM
  2. Laplace transform
    Posted in the Advanced Applied Math Forum
    Replies: 5
    Last Post: December 27th 2010, 11:55 AM
  3. Laplace transform
    Posted in the Differential Equations Forum
    Replies: 4
    Last Post: September 4th 2009, 04:21 AM
  4. Laplace Transform Help
    Posted in the Differential Equations Forum
    Replies: 1
    Last Post: April 9th 2009, 11:50 PM
  5. LaPlace Transform
    Posted in the Calculus Forum
    Replies: 2
    Last Post: November 12th 2008, 11:35 PM

Search Tags


/mathhelpforum @mathhelpforum