Solving for arg(iz) with Example Problem | Complex Numbers Homework Help"

In summary, the problem is to find the argument of the complex number iz, where z=2-i. Using trigonometry, the argument is the angle between the vector from the origin to the complex number and the positive real axis. In this case, the argument would be tan^{-1}(2) or approximately 1.107 radians. However, it is important to note that the complex number given is actually 2-i, so the argument must be found for the number 1+2i, which would still result in the same answer.
  • #1
patm95
31
0

Homework Statement



I need help on a little review please. z=2-i What is arg(iz)


Homework Equations



Well iz= 1+2i


The Attempt at a Solution



I think this should end up being arg(2i/1) But this doesn't seem to make sense because I am wanting to find an angle here right? I am somewhat confused. This is supposed to be an inverse tangent type problem, correct?
 
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  • #2
I am thinking now that this should be something like 3pi/8 but I can't explain my logic...
 
  • #3
It's simple trigonometry if you take a look at a complex number on the argand diagram. The argument of the complex number is the angle between the vector and the x-axis. The vector is just a line between the origin and the complex number.

So, [tex]arg(a+ib)=tan^{-1}(b/a)[/tex]
 
  • #4
Ok. Doesn't that mean that it would be tan-1(2) which would be 1.107?
 
  • #5
No, it doesn't! The arg of a+ bi is the angle the line from 0 to a+bi, thought of as points in the complex plane (a+ bi-> (a, b)) makes with the positive real axis. Specifically it is, as [itex]tan^{-1}(b/a)[/itex] as Mentallic says.

But your number is z= 2- i. a= 2 and b= -1, NOT a= 1 and b= 2 as you seem to think.
 
  • #6
Yeah but the question is what is What is arg(iz) so doesn't that mean that I mult i times 2-i to give me 1+2i?

I think what you just said would be for arg(z). correct?
 
  • #7
Sorry, my fault, I didn't read the problem carefully enough. If z= 2- i then iz= 2i+ 1 so, yes, the arg of 1+ 2i is, in fact, [itex]tan^{-1}(2)[/itex].
 
  • #8
Ok. Thanks!
 

1. What is arg(iz)?

Arg(iz) represents the argument, or angle, of the complex number iz in the complex plane. It is measured in radians and is calculated by taking the inverse tangent of the imaginary component over the real component.

2. How do I solve for arg(iz)?

To solve for arg(iz), you can use the formula arg(iz) = arctan(Im(iz)/Re(iz)), where Im(iz) is the imaginary component of iz and Re(iz) is the real component of iz. You can also use a calculator or a graphing tool to visualize the complex number and find its argument.

3. Can you provide an example problem for solving arg(iz)?

For example, let's say we have the complex number iz = 2i + 3. To solve for arg(iz), we first need to find the imaginary and real components: Im(iz) = 2 and Re(iz) = 3. Plugging these values into the formula, we get arg(iz) = arctan(2/3) ≈ 0.588 radians or approximately 33.69 degrees.

4. Why is solving for arg(iz) important?

The argument of a complex number is important because it helps us understand the position of the number in the complex plane. It also allows us to convert a complex number from rectangular form (in the form a + bi) to polar form (in the form r(cosθ + isinθ)), which can be useful in various applications.

5. Are there any special cases or limitations when solving for arg(iz)?

Yes, there are a few special cases to keep in mind when solving for arg(iz). First, if the complex number is purely real (i.e. has no imaginary component), then arg(iz) = 0. If the complex number is purely imaginary (i.e. has no real component), then arg(iz) = π/2 or 90 degrees. Additionally, the argument of a complex number is not unique, as it can have multiple values depending on the quadrant it lies in. Finally, it's important to note that the argument of a complex number is only defined for non-zero complex numbers.

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