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Math Help - Multiplication of complex exponential numbers

  1. #1
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    Multiplication of complex exponential numbers

    (625e^(3.46i))*(4.4e^(1.22i))

    when i multiply it out i get 2750e^(4.2212i) From there I'm supposed to make it into polar and rectangular forms. the answers in the book are 2750(cos268.1 degrees + i*sin268.1 degrees) for polar form and -89.1 -2750i for rectangular form. Both my answers were incorrect according to the book. So my multiplication must have been off, if anyone can check it for me please.
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by OzzMan View Post
    (625e^(3.46i))*(4.4e^(1.22i))

    when i multiply it out i get 2750e^(4.2212i) From there I'm supposed to make it into polar and rectangular forms. the answers in the book are 2750(cos268.1 degrees + i*sin268.1 degrees) for polar form and -89.1 -2750i for rectangular form. Both my answers were incorrect according to the book. So my multiplication must have been off, if anyone can check it for me please.

    First 3.46+1.22=4.68 not 4.22, so you should have: 2750 e^{4.22i} since:

    (625e^{3.46i})\times (4.4e^{1.22i})=625 \times 4.4 \times e^{(3.46+1.22)i}

    and 4.46 radian is 268.1 degrees (rounded to that precission).

    Of course you should also know that:

    e^{i \theta}=\cos(\theta)+i \sin(\theta)

    RonL
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  3. #3
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    woops i multiplied exponents.
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