What Is the Locus of Points Z in These Complex Number Equations?

In summary, the locus of points satisfying the given equation is the set of all complex numbers z such that the imaginary part of (2iz) is equal to 7 and the absolute value of (z-i) is equal to the real part of z. Solving the equations leads to the solution (y-1)^2=0, which means that the locus of points is a line parallel to the real axis at y=1. This can be seen by drawing a picture on an Argand diagram.
  • #1
gaborfk
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Homework Statement


Describe the locus of points z satisfying the given equation.


Homework Equations


Im(2iz)=7
|z-i|=Re(z)

The Attempt at a Solution


I started on the second one:
I think that Re(z) is just x, then
I squared both sides, simplified and got

(y-1)^2=0 is this correct? If so how would I go about the Im(2iz) LHS on the first equation?

Thank you
 
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  • #2
(y-1)^2=0 is this correct?

That's the right way to start, but you are not quite done yet.

When you squared the equation, you found the solutions of

|z-i| = +Re(z) or |z-i| = -Re(z).

Draw a picture of your solution (y-1)^2 = 0 on an Argand diagram to see what part of it corresponds to |z-i| = +Re(z)

how would I go about the Im(2iz) LHS on the first equation?

Let z = x + iy, then work out what is the imaginary part of (2iz).
 
Last edited:
  • #3
gaborfk said:

Homework Statement


Describe the locus of points z satisfying the given equation.


Homework Equations


Im(2iz)=7
|z-i|=Re(z)

The Attempt at a Solution


I started on the second one:
I think that Re(z) is just x, then
I squared both sides, simplified and got

(y-1)^2=0 is this correct?
And if (y-1)2= 0, what can you say about y?

If so how would I go about the Im(2iz) LHS on the first equation?

Thank you
Pretty much the same thing. Let z= x+iy. What is 2iz in terms of x and y? What is Im(2iz)?
 

FAQ: What Is the Locus of Points Z in These Complex Number Equations?

What are complex numbers and how are they represented in geometry?

Complex numbers are numbers that consist of a real part and an imaginary part, represented as a + bi, where a and b are real numbers and i is the imaginary unit. In geometry, complex numbers are represented as points on a two-dimensional plane, with the x-coordinate representing the real part and the y-coordinate representing the imaginary part.

How are operations like addition, subtraction, multiplication, and division performed on complex numbers in geometry?

In geometry, addition and subtraction of complex numbers are performed by adding or subtracting the real and imaginary parts separately. Multiplication of complex numbers is done by using the distributive property, and division is done by multiplying the complex number by its conjugate.

What is the geometric interpretation of the modulus and argument of a complex number?

The modulus of a complex number is its distance from the origin on the complex plane, and the argument is the angle it makes with the positive real axis. This can also be thought of as the magnitude and direction of the complex number in polar form.

How are complex numbers used in geometric transformations?

Complex numbers are used to represent transformations such as translations, rotations, reflections, and dilations in the complex plane. These transformations can be visualized and computed using complex number operations.

Can complex numbers be used to solve geometric problems?

Yes, complex numbers can be used to solve geometric problems such as finding the coordinates of points, determining the distance between points, and finding the equations of lines and circles on the complex plane.

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