Solve Complex Equation: Find Z, K in \frac{Z-a}{Z-b}=Ke^{±jθ}

In summary, the conversation is about finding a solution for the equation involving unknown complex numbers, using the given conditions for different values of theta. The speaker is unsure about how to solve it and apologizes for posting in the wrong area. They also mention getting only one solution, even though there should be more based on the given formula with a \pm.
  • #1
powers
2
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Hi, I need a little help :smile:

I need to find solution for this equations:

[itex]\frac{Z-a}{Z-b}[/itex]=K[itex]e^{±jθ}[/itex]

The Z is unknown and it is the complex number. The a and b is known and they are also complex numbers. K is the real number.

I know that for [itex]-90^{°}[/itex]<θ<[itex]90^{°}[/itex] the graph in the complex plane is circle, for [itex]-45^{°}[/itex]<θ<[itex]45^{°}[/itex] the graph in the complex plane is in shape of "tomato" and for [itex]-135^{°}[/itex]<θ<[itex]135^{°}[/itex] is shape of "lens", but I don't know how to solve it.

Sorry if my post is in wrong area.

Thanks for help.
 
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  • #2
Leaving it to you the conditions of existence:

[itex]Z=\frac{a-b.K.\textrm{e}^{ \pm j \theta }}{1-K.\textrm{e}^{ \pm j \theta }}[/itex]
 
  • #3
In that way I got only the one solution, where are the other?
For example, let's put b=0, K=1, theta=45°, with above formula we got only the one solution, but there is more than one solution...
 
  • #4
How do you only get one solution when there's clearly a [itex]\pm[/itex] in his answer?
 
  • #5


To solve this complex equation, we can begin by multiplying both sides by (Z-b) to eliminate the fraction. This gives us:

Z-a=K(Z-b)e^{±jθ}

Next, we can distribute the K and the e^{±jθ} terms to get:

Z-a=KZe^{±jθ}-Kbe^{±jθ}

Now, we can rearrange the equation to isolate Z on one side:

Z-KZe^{±jθ}=a-Kbe^{±jθ}

Next, we can factor out Z from the left side:

Z(1-Ke^{±jθ})=a-Kbe^{±jθ}

Finally, we can solve for Z by dividing both sides by (1-Ke^{±jθ}):

Z=\frac{a-Kbe^{±jθ}}{1-Ke^{±jθ}}

This equation gives us the solution for Z in terms of a, b, K, and θ. To find the specific values for Z and K, we will need to plug in the given values for a, b, and θ. This will give us a complex number for Z and a real number for K.

I hope this helps and feel free to ask for any clarification. Remember, solving complex equations can be tricky, so always double check your work and make sure to follow the order of operations. Good luck!
 

1. What is the purpose of solving a complex equation?

Solving a complex equation allows us to find the values of the variables involved in the equation and determine the relationship between them. This can provide valuable insights and help us understand the behavior of the system or process described by the equation.

2. What do Z and K represent in the given equation?

Z and K are variables that represent complex numbers in the equation. Z can be any complex number, while K is a constant complex number that multiplies the exponential term.

3. How do we find the values of Z and K in the equation?

To find the values of Z and K, we need to first isolate them on one side of the equation. This can be done by first multiplying both sides by the denominator (Z-b) and then simplifying the resulting equation. We can then compare the real and imaginary parts of the equation to get the values of Z and K.

4. What is the significance of the exponential term in the equation?

The exponential term (e^±jθ) represents a complex number in polar form. The value of θ determines the angle at which the complex number is located on the complex plane, while the exponential term itself represents the magnitude or distance of the number from the origin. This term is often used to describe oscillating or rotating phenomena in science and engineering.

5. Can this equation be solved for any value of θ?

Yes, this equation can be solved for any value of θ. However, the resulting values of Z and K may be different depending on the value of θ. This is because the exponential term affects the values of Z and K, and different values of θ will change the magnitude and angle of the exponential term.

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