What is the Locus of Points for 2π|z - 1| = Arg(z - 1) in an Argand Diagram?

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Homework Help Overview

The problem involves finding the locus of points that satisfy the equation 2π|z - 1| = Arg(z - 1) within the constraint |z - 1| ≤ 2 in the context of complex numbers represented in an Argand diagram.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants discuss the geometric interpretation of the constraint |z - 1| ≤ 2 as representing points inside a circle centered at (1,0) with radius 2. There is confusion regarding the implications of Arg(z - 1) and its range, with some questioning how it relates to the overall space defined by the circle. A suggestion is made to shift the origin to simplify the equations, leading to a transformation of the problem.

Discussion Status

Participants are exploring different interpretations of the equations and their implications. Some have proposed using a substitution to analyze the problem further, while others are questioning the correctness of transformations and the resulting plots. There is no explicit consensus on the final approach yet, but the discussion is progressing with clarifications being made.

Contextual Notes

There is an ongoing discussion about the assumptions related to the argument of complex numbers and how shifting the origin affects the equations. Participants are also considering the implications of the spiral nature of the locus derived from the equations.

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Homework Statement



Find the locus of points which satisfy

2π*|z −1| = Arg(z − 1) where |z −1| ≤ 2.

Homework Equations



n/a

The Attempt at a Solution



I know that |z-1| ≤ 2 is the 'inside' bits of a circle center (1,0) with a radius 2

After that I get confused surely with |z-1|≤2 then Arg(z-1) has to be between 0 and 4π... but then that's all space?

Thanks in advance
 
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Gone said:

Homework Statement



Find the locus of points which satisfy

2π*|z −1| = Arg(z − 1) where |z −1| ≤ 2.

Homework Equations



n/a

The Attempt at a Solution



I know that |z-1| ≤ 2 is the 'inside' bits of a circle center (1,0) with a radius 2

After that I get confused surely with |z-1|≤2 then Arg(z-1) has to be between 0 and 4π... but then that's all space?

Thanks in advance

Since everything is with reference to ##1+0i##, it would be good idea to shift the origin here. Shifting the origin, your equations transform to:
$$2\pi |z|=\arg(z)$$
$$|z|\leq 2$$
Use the substitution ##z=re^{i\theta}## in the first equation, do you see where that leads to?
 
Pranav-Arora said:
Since everything is with reference to ##1+0i##, it would be good idea to shift the origin here. Shifting the origin, your equations transform to:
$$2\pi |z|=\arg(z)$$
$$|z|\leq 2$$
Use the substitution ##z=re^{i\theta}## in the first equation, do you see where that leads to?

So that means that ##2\pi r=\theta## which is a spiral beginning at (0,0) so to get the answer is it just
$$2\pi (r-1)=\theta$$
Thanks!
 
Gone said:
So that means that ##2\pi r=\theta## which is a spiral beginning at (0,0)
Yes.
so to get the answer is it just
$$2\pi (r-1)=\theta$$
Well, no. I don't think that transformation is correct. Once you plot the graph, you need to move everything by 1 unit towards right.

Look at the plots of ##2\pi r=\theta## and ##2\pi (r-1)=\theta##.
 
Ah ok got you now :) thank you!
 

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