Math Problem Statement

(|z| = 2) (\arg(z) = -\frac{2}{3}\pi) The polar form is: [ z = |z| \left( \cos(\arg(z)) + i \sin(\arg(z)) \right) ]

Solution

Given the modulus z=2|z| = 2 and the argument arg(z)=23π\arg(z) = -\frac{2}{3}\pi, we can express zz in its polar form using the following formula:

z=z(cos(arg(z))+isin(arg(z)))z = |z| \left( \cos(\arg(z)) + i \sin(\arg(z)) \right)

Substituting the given values:

z=2(cos(23π)+isin(23π))z = 2 \left( \cos\left(-\frac{2}{3}\pi\right) + i \sin\left(-\frac{2}{3}\pi\right) \right)

Step 1: Calculate cos(23π)\cos\left(-\frac{2}{3}\pi\right)

Using the cosine function: cos(23π)=cos(23π)=12\cos\left(-\frac{2}{3}\pi\right) = \cos\left(\frac{2}{3}\pi\right) = -\frac{1}{2}

Step 2: Calculate sin(23π)\sin\left(-\frac{2}{3}\pi\right)

Using the sine function: sin(23π)=sin(23π)=32\sin\left(-\frac{2}{3}\pi\right) = -\sin\left(\frac{2}{3}\pi\right) = -\frac{\sqrt{3}}{2}

Step 3: Write the complex number in polar form

Now, substituting these values into the formula: z=2(12+i(32))z = 2 \left( -\frac{1}{2} + i \left( -\frac{\sqrt{3}}{2} \right) \right) Simplifying: z=1i3z = -1 - i\sqrt{3}

Thus, the complex number in standard form is: z=1i3z = -1 - i\sqrt{3}

Would you like any further clarifications or details?

Here are five related questions for further exploration:

  1. How do you convert from polar form to exponential form of a complex number?
  2. What is the geometric interpretation of the argument of a complex number?
  3. How do you multiply two complex numbers in polar form?
  4. How do you find the argument of a complex number located in the third or fourth quadrant?
  5. What is the relation between Cartesian form and polar form of complex numbers?

Tip: When working with complex numbers, always be mindful of the quadrant to correctly determine the sign of sine and cosine.

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Polar Form
Trigonometry

Formulas

z = |z| \left( \cos(\arg(z)) + i \sin(\arg(z)) \right)
cos(\theta) and sin(\theta) for standard angles

Theorems

Euler's Formula

Suitable Grade Level

Grades 10-12