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!

Trig Please Help me

  1. Jul 21, 2010 #1
    1. The problem statement, all variables and given/known data

    What does cis^-1 (x) mean
    like you know how there is sin^-1 (x) and sin(x) applying that concept with cis(x) what does that mean?

    Note that is not a spelling mistake I'm not trying to say cos^-1 (x) I'm indeed saying cis^-1 (x) with an "i"

    I also wander what does cis stand for like cos is cosine sin is sine etc. how do I say cis...

    like I was thinking ok

    cis(x) = cos(x) + i sin(x) = e^(ix)
    what does cis^-1(x) mean

    kind of stuck here...

    Thank You

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Jul 21, 2010 #2
    Since cis(x) is defined in the following manner,

    [tex]cis(x) = cos(x) +isin(x) = e^{ix}[/tex]

    Simply take the inverse of cis(x),

    [tex]cis^{-1}(x) = \pm cos^{-1}(\frac{x^{2} + 1}{2x})[/tex]
    Last edited: Jul 21, 2010
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook