If `veca and vecb` are unit vectors, then find the greatest value of `|veca+vecb|+ |veca-vecb|` .

Explanation

To find the greatest value of \( |\vec{a} + \vec{b}| + |\vec{a} - \vec{b}| \) where \(\vec{a}\) and \(\vec{b}\) are unit vectors, we can follow these steps:

### Step 1: Understand the properties of unit vectors
Since \(\vec{a}\) and \(\vec{b}\) are unit vectors, we know that:
\[ |\vec{a}| = 1 \quad \text{and} \quad |\vec{b}| = 1 \]

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