Complex Conjugated Poles

Discussion in 'Homework Help' started by bserrato86, Apr 22, 2009.

  1. bserrato86

    Thread Starter New Member

    Apr 18, 2009
    So I'm studying for a test and I'm not sure how an answer was derived based on the previous number. Could someone tell me how the answer came about?

    [10*(j1)] / [(-2+j1)*(j2)]

    The Answer is:

    5 / [2.24 angle(153.43*)]

    The final answer is in polar form but I don't get how it came about. I tried to solve it and it didn't work. Could someone show me the steps?

    I tried solving the bottom part by distribution:

    (-4j + j^2 2) = (-2 - j4) = 4.47 angle(-63.43)

    The top I didn't really know how it came to it. This part is of course part of the bigger problem but I don't understand how this part came about. I've included the slide I got it from & circled where I got stuck. Could someone help me understand?
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    Ignoring the (-2+j1) term for the moment you would have


    The j terms in the numerator and denominator cancel and you are left with 10/2 or 5.

    So re-introducing the (-2+j1) term in the denominator would give you

    5/(-2+j1) and since (-2+j1) = √5 angle(153.43°) = 2.24 angle(153.43°)

    you now have

    5/(2.24 angle(153.43°)