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Math Help - complex numbers help please

  1. #1
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    complex numbers help please

    Draw the points A : i
    and the point B: (1/(20.5)) + (1/(20.5))i on a argand digram and hence find the argument of A+B i drew it but i am clueless
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  2. #2
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    Re: complex numbers help please

    Quote Originally Posted by righteous818 View Post
    Draw the points A : i
    and the point B: (1/(20.5)) + (1/(20.5))i on a argand digram and hence find the argument of A+B i drew it but i am clueless
    \arg (i) = \frac{\pi }{2}\;\& \;\arg \left( {\frac{{\sqrt 2 }}{2} + \frac{{\sqrt 2 }}{2}i} \right) = \frac{\pi }{4}

    The \arg(A+B)=\arctan\left(\frac{\sqrt2+2}{\sqrt2} \right)
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  3. #3
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    Re: complex numbers help please

    they the mark scheme has 3pi/8 and specifically gave no marks for using that forumla and approximating the answer to 3pi/8, they said not to use that formula, they stressed to use the argand diagram to find it, any suggestions how, i did this first but then realised that they did not accept this method..please help


    i forgot to mention they want the argument exactly in terms of pi, and have no marks for find A+B and finidnging the argument from that
    Last edited by righteous818; April 22nd 2013 at 10:43 AM.
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  4. #4
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    Re: complex numbers help please

    complex numbers help please-argand2.png

    Note that OACB is a parallelogram, and thus OC is the bisector of ∠AOB.
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  5. #5
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    Re: complex numbers help please

    what is the program you use to plot the function an show it is a paralleogram
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  6. #6
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    Re: complex numbers help please

    To draw the diagram I used TikZ, and to prove that it is a parallelogram I used my wetware.
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