Important Modulus Identity

Important Modulus Identity

## Formula

$$|z_1+z_2|^2+|z_1-z_2|^2=2(|z_1|^2+|z_2|^2)$$

## Terminologies

- Parallelogram law → Identity relating the lengths of the sum and difference of two complex vectors.

## Usage

- Used in complex-number modulus problems involving sums and differences.