1
   

Complex Numbers Question

 
 
Rigby
 
Reply Thu 28 Apr, 2005 08:31 pm
I've just got a quick question about complex numbers.

I know you can turn any complex number from olar form into cartesian form and thus plot a vector of that complex number onto the argand plane, but is it possible for me to turn an argument into a cartesian equation?

I'm only asking this question because I recently was confronted with a problem that told me to find the cartesian equation of arg(z+2+i) = -pi/6 by letting z=x+iy
Anyways, a few lines of algebra later, I get the solution:
y=-1/(3^1/2)x-2/(3^1/2)-1 , x>-2
which has no imaginary part, so can this still be technically be called the cartesian equation? Is it that I just have a mixed up definition of cartesian equation?

I always thought that cartesian equations, geometrically, were drawn from the origin and then to the corresponding point on the argand plane, but with an argument there is no corresponding point to draw to, so you go to infinity. Is this allowed?
  • Topic Stats
  • Top Replies
  • Link to this Topic
Type: Discussion • Score: 1 • Views: 490 • Replies: 1
No top replies

 
raprap
 
  1  
Reply Fri 29 Apr, 2005 06:36 am
I'm afraid I don't completely understand your question for two reasons.

When I rearrange z+2+i=-pi/6 when z=x+iy I get
y=-1+y(x+2+pi/6) not the relation expressed.

In addition I saw the expressed relationship as the line y=Ax+B with A=-1/sqrt(3) and B=-[(1+sqrt(3))/sqrt(3)]

Back to complex and the cartesian coordinates.

With z=x+iy look at the composite number z as having a real and an imaginary part, with the real number as the x (horizontal) axis and the imaginary part as the y (vertical) axis. z then is a line that goes through the origon (x intercept is 0).

If you look at the magnitude of z (|z|) the z=x+iy can be viewed as a vector of the magnitude of z on a unit circle on the x y plane where

z=|z|(cos(phi)+isin(phi)) where cos(phi)=x/|z| and sin(phi)=y/|z| and cos(phi)+isin(phi)=|1| is a unit circle.

Mathworld gives a much better explanation of complex numbers than can be done in the limited html of this forum. I would recommend looking at this page.

Rap
0 Replies
 
 

Related Topics

Evolution 101 - Discussion by gungasnake
Typing Equations on a PC - Discussion by Brandon9000
The Future of Artificial Intelligence - Discussion by Brandon9000
The well known Mind vs Brain. - Discussion by crayon851
Scientists Offer Proof of 'Dark Matter' - Discussion by oralloy
Blue Saturn - Discussion by oralloy
Bald Eagle-DDT Myth Still Flying High - Discussion by gungasnake
DDT: A Weapon of Mass Survival - Discussion by gungasnake
 
  1. Forums
  2. » Complex Numbers Question
Copyright © 2025 MadLab, LLC :: Terms of Service :: Privacy Policy :: Page generated in 0.03 seconds on 01/20/2025 at 05:19:26