Turning Complex Number z into Polar Form

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Homework Help Overview

The discussion revolves around converting a complex number, specifically derived from the equation \(\frac{z-1}{z+1}=i\), into polar form after finding its Cartesian representation as \(z = i\). The subject area involves complex numbers and their representations in different forms.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the conversion of the complex number \(z = i\) into polar form, discussing its magnitude and angle. Questions arise regarding the clarity of the problem statement and the assumptions made about the given equation.

Discussion Status

There is an ongoing exploration of how to express the complex number in polar form, with some participants providing guidance on identifying the magnitude and angle. Multiple interpretations of the problem statement are being discussed, and there is no explicit consensus on the clarity of the initial question.

Contextual Notes

Participants note the importance of clearly stating the problem and the assumptions involved, as well as the potential confusion regarding the definitions of magnitude and angle in the context of polar coordinates.

mr-feeno
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Homework Statement


\frac{z-1}{z+1}=i
I found the cartesian form, z = i, but how do I turn it into polar form?

The Attempt at a Solution


|z|=\sqrt{0^2+1^2}=1
\theta=arctan\frac{b}{a}=arctan\frac{1}{0}

Is the solution then that is not possible to convert it to polar form?
 
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mr-feeno said:

Homework Statement


\frac{z-1}{z+1}=i
I found the cartesian form, z = i, but how do I turn it into polar form?

The Attempt at a Solution


|z|=\sqrt{0^2+1^2}=1
\theta=arctan\frac{b}{a}=arctan\frac{1}{0}

Is the solution then that is not possible to convert it to polar form?

Notice that ##\tan(\frac{\pi}{2} + k \pi)## with ## k \in \mathbb{Z}## is not defined. Draw ## i ## in the complex plane. What can you conclude?
 
mr-feeno said:

Homework Statement


\frac{z-1}{z+1}=i
I found the cartesian form, z = i, but how do I turn it into polar form?
What is the exact problem statement? Are you given that ##\frac{z-1}{z+1}=i##?

Doing some work on this, it appears that if ##\frac{z-1}{z+1}=i##, then ##z = i##
It would have been helpful to me for you to say what is given, and what you needed to do.
mr-feeno said:

The Attempt at a Solution


|z|=\sqrt{0^2+1^2}=1
\theta=arctan\frac{b}{a}=arctan\frac{1}{0}

Is the solution then that is not possible to convert it to polar form?
It's easy to convert to polar form. What is |i|?
What is the angle that i makes with the horizontal axis?
 
Mark44 said:
What is the exact problem statement? Are you given that ##\frac{z-1}{z+1}=i##?

Doing some work on this, it appears that if ##\frac{z-1}{z+1}=i##, then ##z = i##
It would have been helpful to me for you to say what is given, and what you needed to do.

It's easy to convert to polar form. What is |i|?
What is the angle that i makes with the horizontal axis?
90\circ? I felt it was clear
|z| is the length
 
mr-feeno said:
90\circ? I felt it was clear
|z| is the length

The angle is ##\pi/2##, in radians, or 90°.
The magnitude is NOT |z|. I asked what is the magnitude of i?

No, it wasn't clear.

Clear would be something like this:
If ##\frac{z - 1}{z + 1} = i##, solve for z, writing it in polar form.
 
Mark44 said:
The angle is ##\pi/2##, in radians, or 90°.
The magnitude is NOT |z|. I asked what is the magnitude of i?

No, it wasn't clear.

Clear would be something like this:

Ok, my bad. But thanks :)
 
mr-feeno said:
Ok, my bad. But thanks :)
You're welcome!
 

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