Math Problem Statement

z satisfies mod(z-2-2i)=2 and arg(z-2-2i)=pi/6, find z

Solution

We are tasked with finding a complex number zz that satisfies the following two conditions:

  1. z(2+2i)=2|z - (2 + 2i)| = 2
  2. arg(z(2+2i))=π6\arg(z - (2 + 2i)) = \frac{\pi}{6}

Step 1: Representing zz in terms of a shifted complex number

Let: w=z(2+2i)w = z - (2 + 2i) This means we are looking for ww such that:

  • w=2|w| = 2
  • arg(w)=π6\arg(w) = \frac{\pi}{6}

Step 2: Using the polar form of complex numbers

From polar coordinates, we know that any complex number ww can be expressed as: w=r(cosθ+isinθ)w = r(\cos \theta + i \sin \theta) where rr is the magnitude and θ\theta is the argument of ww.

Given that w=2|w| = 2 and arg(w)=π6\arg(w) = \frac{\pi}{6}, we have: w=2(cosπ6+isinπ6)w = 2\left( \cos\frac{\pi}{6} + i \sin\frac{\pi}{6} \right)

Step 3: Simplifying the expression for ww

We now calculate the trigonometric values: cosπ6=32,sinπ6=12\cos\frac{\pi}{6} = \frac{\sqrt{3}}{2}, \quad \sin\frac{\pi}{6} = \frac{1}{2} Thus, ww becomes: w=2(32+i12)w = 2\left( \frac{\sqrt{3}}{2} + i \cdot \frac{1}{2} \right) w=3+iw = \sqrt{3} + i

Step 4: Finding zz

Since w=z(2+2i)w = z - (2 + 2i), we have: z(2+2i)=3+iz - (2 + 2i) = \sqrt{3} + i Solving for zz: z=(3+i)+(2+2i)z = (\sqrt{3} + i) + (2 + 2i) z=3+2+(1+2)iz = \sqrt{3} + 2 + (1 + 2)i z=(3+2)+(3i)z = (\sqrt{3} + 2) + (3i)

Thus, the complex number zz is: z=3+2+3iz = \sqrt{3} + 2 + 3i

Final Answer:

z=3+2+3iz = \sqrt{3} + 2 + 3i

Would you like further details or have any questions?


Here are 5 related questions:

  1. How do we find the modulus of a complex number?
  2. What is the geometric interpretation of the argument of a complex number?
  3. How can we express a complex number in polar form?
  4. How does adding a complex number shift it in the complex plane?
  5. What is the connection between Euler's formula and polar representation?

Tip: When solving complex number problems, converting between rectangular and polar forms can simplify operations like multiplication, division, and finding powers or roots.

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Math Problem Analysis

Mathematical Concepts

Complex Numbers
Modulus and Argument of Complex Numbers
Polar Coordinates

Formulas

|z - (a + bi)| = r
z = r(cos θ + i sin θ)

Theorems

Polar Form of Complex Numbers
Argument and Modulus of a Complex Number

Suitable Grade Level

Grades 10-12