Geometric interpetation of a complex number in R^2

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Homework Help Overview

The problem involves understanding the geometric interpretation of complex numbers in the context of \(\mathbb{R}^2\). The original poster is given two complex numbers, \(Z_1\) and \(Z_2\), and their sum \(Z_3\), and is exploring how to represent these numbers graphically in a two-dimensional real coordinate system.

Discussion Character

  • Exploratory, Conceptual clarification

Approaches and Questions Raised

  • The original poster questions how to graph complex numbers in \(\mathbb{R}^2\) and whether they should simply take the real part to plot points. They also express uncertainty about which axis to use and consider the possibility of a typo in the problem statement.

Discussion Status

Some participants have confirmed that complex numbers can be represented as vectors in \(\mathbb{R}^2\), specifically noting that the complex number \(a + bi\) corresponds to the vector \((a, b)\). The conversation appears to be moving towards a clearer understanding of this representation, although the original poster still expresses some confusion about the transition from the complex plane to \(\mathbb{R}^2\).

Contextual Notes

The discussion includes considerations of how complex numbers are typically plotted in the complex plane versus their representation in a real coordinate system, highlighting potential misunderstandings about the axes involved.

Valhalla
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For this problem i am given two complex numbers [tex]Z_1 , Z_2[/tex] and then a third which is the sum of the first two complex numbers [tex]Z_3[/tex]. I am then asked to find the geometric interpetation of these numbers in [tex]\mathbb{R}^2[/tex]. I am fine when graphing them in the complex plane but unsure of what they look like in [tex]\mathbb{R}^2[/tex]. Do I just take the real part and graph a point in the [tex]\mathbb{R}^2[/tex]? If so how do I determine which axis it would be on? Do you think this might be a typo?
 
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The standard "complex plane" is to plot the complex number a+ bi as the point (a, b). That is, the x-axis is the "real axis" and the y-axis is the "imaginary axis". It might occur to you that the sum of complex numbers, (a+ bi)+ (c+ di)= (a+c)+ (b+d)i looks a lot like (a+c, b+d), the sum of vectors. And that might lead you to think about a parallelogram.
 
HallsofIvy said:
The standard "complex plane" is to plot the complex number a+ bi as the point (a, b). That is, the x-axis is the "real axis" and the y-axis is the "imaginary axis". It might occur to you that the sum of complex numbers, (a+ bi)+ (c+ di)= (a+c)+ (b+d)i looks a lot like (a+c, b+d), the sum of vectors. And that might lead you to think about a parallelogram.


Yes, I understand that the complex numbers add like vectors. However, what I am confused about is that I thought that to graph them they needed to be in the complex plane. Like you said the x-axis is the real and the y-axis is the imaginary. When I look at the complex number (a+bi) and consider where that would be on R^2, I get confused.

So if I get what your saying then the complex number (a+bi) would just be the vector (a,b) in R^2? Am I overthinking this?
 
Yes, that's exactly what I am saying!
 
Ok I think I got it then. Thanks HallsofIvy!
 

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