Prove that `|overset(rarr)a-overset(b)|ge||overset(rarr)a|-|overset(rarr)b||` When does the equally holds?

Explanation

To prove the inequality \( |\vec{a} - \vec{b}| \geq ||\vec{a}| - |\vec{b}|| \), we will follow these steps:

### Step 1: Understand the expression
We need to show that the magnitude of the difference between two vectors \( \vec{a} \) and \( \vec{b} \) is always greater than or equal to the absolute difference of their magnitudes.

### Step 2: Square both sides
To simplify the comparison, we will square both sides of the inequality:
\[
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