Argand Plane

Rarely Tested

Argand Plane

## Definition / Concept

A complex number $z=a+ib$ is represented by the point $(a,b)$ in a two-dimensional plane.

## Terminologies

- Real axis → Horizontal axis representing real parts.

- Imaginary axis → Vertical axis representing imaginary parts.

- Affix → Point representing a complex number in the Argand plane.

## Formula

For:

$$z=a+ib$$

the corresponding point is:

$$(a,b)$$

The distance from the origin is:

$$|z|=\sqrt{a^2+b^2}$$

## Conditions / Special Cases

If:

$$b=0$$

the point lies on the real axis.

If:

$$a=0$$

the point lies on the imaginary axis.

## Usage

- Used to visualize complex numbers geometrically.

- Used to solve locus and argument problems.

Question 1

If $$z$$ is a complex number satisfying $$\left|\frac{z-2}{z+2}\right|=1,$$ then the  minimum value of $$|z|^2-4\operatorname{Re}(z)$$ is ______.

Question 2

Let $$z = 1 + i$$. Define a new complex number $$z_1$$ as follows:

$$z_1 = \frac{1 + i\bar{z}}{\bar{z}(1 - z) + \frac{1}{z}}$$

Then the value of $$\frac{12}{\pi} \arg(z_1)$$ is equal to:

Question 3

If $$z = re^{i\theta}$$ is a complex number such that $$|z - 1| = 1$$ and $$|z - i| = 1,$$ find $$|z|.$$

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