Results 1 to 2 of 2

Math Help - Complex numbers: express in modulus-argument form (cis)

  1. #1
    Newbie
    Joined
    Feb 2011
    Posts
    14

    Complex numbers: express in modulus-argument form (cis)

    1 + cot(x)i , express in modulus argument form where 0 < x < pi/2

    I understand how to get the modulus by finding (1 + cot^2(x))^1/2 = cosec(x)

    but the answer gives cosec(x)cis(pi/2 - x), i dont understand why the (pi/2 - x) is needed and not just cis(x).
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,404
    Thanks
    1293
    Length: \displaystyle \sqrt{1 + \cot^2{x}} = \sqrt{\csc^2{x}} = \csc{x}.

    Angle: \displaystyle \arctan{\left(\frac{\cot{x}}{1}\right)} = \arctan{(\cot{x})} = \arctan{\left[\tan{\left(\frac{\pi}{2} - x\right)}\right]} = \frac{\pi}{2} - x.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Complex Numbers - Argument of Z
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: February 9th 2011, 02:37 AM
  2. Replies: 2
    Last Post: July 31st 2010, 02:43 AM
  3. Complex numbers: Argument of Z help
    Posted in the Pre-Calculus Forum
    Replies: 8
    Last Post: August 6th 2009, 10:57 PM
  4. Replies: 6
    Last Post: June 20th 2009, 07:40 AM
  5. modulus-argument form
    Posted in the Calculus Forum
    Replies: 8
    Last Post: October 3rd 2008, 10:05 AM

Search Tags


/mathhelpforum @mathhelpforum