Find the angle between two vectors ` vec a` , `vec b` having the same length `sqrt(2)` and their scalar product is `-1`.

Explanation

To find the angle between two vectors \( \vec{a} \) and \( \vec{b} \) given that they have the same length \( \sqrt{2} \) and their scalar product \( \vec{a} \cdot \vec{b} = -1 \), we can follow these steps:

### Step 1: Use the formula for the scalar product
The scalar product (dot product) of two vectors can be expressed as:
\[ \vec{a} \cdot \vec{b} = |\vec{a}| |\vec{b}| \cos \theta \]
where \( |\vec{a}| \) and \( |\vec{b}| \) are the magnitudes of the vectors, and \( \theta \) is the angle between them.
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