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    Hey guys I need help with Edexcel FP2 exercise 3H question 15

    can some one please go through it with me , thanks in advance
    question:
    the transformation T from the z-plane, where z=x+iy, to the w-plane where w = u + iv, is given by : w = z + 4/z

    show that the transformation T maps the points on a circle with modulus 2 (mod(z)=2 i.e centre 0,0 ) to the points in the interval [-k,k] on the real axis, state the value of the constant k.
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    Write z in polar form using |z|=2 then sub into the transformation.
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    (Original post by james22)
    Write z in polar form using |z|=2 then sub into the transformation.
    I did ( |z|=2 came with the question) but im not sure how to sub it in
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    (Original post by nmanvi)
    I did ( |z|=2 came with the question) but im not sure how to sub it in
    What is the general form of a complex number in polar form?
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    (Original post by james22)
    What is the general form of a complex number in polar form?
    I am not sure I havent done any polar coordinates, in the middle of complex numbers
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    (Original post by nmanvi)
    I am not sure I havent done any polar coordinates, in the middle of complex numbers
    Have you seen things like e^{ix} or \cos(x)+i\sin(x)?
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    (Original post by james22)
    Have you seen things like e^{ix} or \cos(x)+i\sin(x)?
    yeppp, will they help me answer the question?
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    (Original post by nmanvi)
    yeppp, will they help me answer the question?
    Yes, you should know that any complex number can be written in the form z=r\cos(x)+r\sin(x) where r is the modulus of z.

    EDIT: You also need that cos(x)+isin(x)=e^ix.
 
 
 
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