Math Problem Statement

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Based on the image, determine the complex number Z represented in polar form on the complex plane.

Solution

Let's analyze the image.

The problem involves a complex number ZZ represented in polar form on the complex plane with coordinates provided in terms of the real and imaginary parts.

From the diagram:

  1. The real part (x-axis) is 12\frac{1}{2}.
  2. The imaginary part (y-axis) is 32-\frac{\sqrt{3}}{2}.

The complex number ZZ can be represented as: Z=1232iZ = \frac{1}{2} - \frac{\sqrt{3}}{2} i

Step 1: Calculate the modulus Z|Z|

The modulus Z|Z| is given by: Z=(12)2+(32)2=14+34=1=1|Z| = \sqrt{\left( \frac{1}{2} \right)^2 + \left( -\frac{\sqrt{3}}{2} \right)^2} = \sqrt{\frac{1}{4} + \frac{3}{4}} = \sqrt{1} = 1 Thus, Z=1|Z| = 1, confirming that ZZ lies on the unit circle.

Step 2: Determine the argument φ\varphi

The argument φ\varphi is the angle that ZZ makes with the positive x-axis. Given that the coordinates are (12,32)\left( \frac{1}{2}, -\frac{\sqrt{3}}{2} \right), we are in the fourth quadrant.

For these values: cos(φ)=12andsin(φ)=32\cos(\varphi) = \frac{1}{2} \quad \text{and} \quad \sin(\varphi) = -\frac{\sqrt{3}}{2} This corresponds to an angle φ=5π3\varphi = \frac{5\pi}{3} radians (since in the fourth quadrant, we subtract from 2π2\pi).

Step 3: Write ZZ in polar form

Using φ=5π3\varphi = \frac{5\pi}{3}, we can write ZZ as: Z=cos(5π3)+isin(5π3)Z = \cos\left(\frac{5\pi}{3}\right) + i \sin\left(\frac{5\pi}{3}\right)

Answer Selection

From the given options, the correct answer is:

  • e. Z=cos(5π3)+isin(5π3)Z = \cos\left(\frac{5\pi}{3}\right) + i \sin\left(\frac{5\pi}{3}\right)

Final Answer:

Option (e) is correct.

Would you like further clarification or details?


Here are some additional questions related to this topic:

  1. How do you convert a complex number from Cartesian to polar form?
  2. Why does the argument φ\varphi differ based on the quadrant?
  3. How can you determine the quadrant of a complex number from its Cartesian coordinates?
  4. What is the geometric interpretation of the modulus and argument of a complex number?
  5. How do we apply trigonometric identities to find polar coordinates?

Tip: Remember that converting between polar and Cartesian forms often involves using trigonometric functions like cosine and sine for the respective real and imaginary parts.

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Polar Coordinates
Trigonometry

Formulas

Polar form of a complex number: Z = r * (cos(φ) + i * sin(φ))
Modulus formula: |Z| = sqrt(x^2 + y^2)
Argument calculation: φ = arctan(y/x)

Theorems

Pythagorean theorem for modulus calculation
Trigonometric identities for polar representation

Suitable Grade Level

Grades 10-12