If I have given that the absolute value of Z

Answered question

2022-01-17

If I have given that the absolute value of Z is 1. how do I prove the z+1z is re and z1z is Im?

Answer & Explanation

nick1337

nick1337

Expert2022-01-17Added 777 answers

Step 1
There are two things to note, if
|z|=1,
then
1z=z(conjugate of z) and
z+z=2re(z) and
zz=2im(z)
1z=zzz( multiply top and bottom by z)
=z1=z
Therefore
\(z+\frac{1}{z}=z+z

star233

star233

Skilled2022-01-17Added 403 answers

Step 1
Make a picture of the situation in the complex plane. You probably know that the absolute value of
1z is also 1,
and you should know that the angle that 1z makes with the x axis is the same size but of opposite rotational direction as the angle made by z.
It’ll come to you.

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