Results 1 to 5 of 5

Math Help - re^itheta

  1. #1
    Super Member
    Joined
    Feb 2008
    Posts
    535

    re^itheta

    I'm asked to express 4 in the form re^i*theta

    Here's what i've done:

    r = squreRoot(4^2 + 0^2)
    r = 4

    How do I find theta?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Aug 2009
    From
    Israel
    Posts
    976
    4 = 4 +0\cdot i, so \theta = arctan \left( \frac{0}{4} \right) = arctan(0)
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Super Member
    Joined
    Feb 2008
    Posts
    535
    Ok, then 4 written in this form is just simply 4 since 4e^i*0 = 4. RIght?

    How about this one: 3i

    r = 3, but theta = arctan(3/0)??? 3 divided by 0...
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    10,969
    Thanks
    1009
    Well, 3i lies on the positive imaginary axis.

    What is the angle made?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by jzellt View Post
    I'm asked to express 4 in the form re^i*theta

    Here's what i've done:

    r = squreRoot(4^2 + 0^2)
    r = 4

    How do I find theta?
    Quote Originally Posted by jzellt View Post
    [snip]
    How about this one: 3i

    r = 3, but theta = arctan(3/0)??? 3 divided by 0...
    If you had plotted 4 and 3i on an Argand diagram it would be completely obvious what the argument of each is.
    Follow Math Help Forum on Facebook and Google+

Search Tags


/mathhelpforum @mathhelpforum