If `veca and vecb` are two vectors, such that `|veca xx vecb|=2` , then find the value of `[veca vecb veca] xx vecb` .

Explanation

To solve the problem, we need to find the value of the expression \([ \vec{a} \, \vec{b} \, \vec{a} ] \times \vec{b}\), given that \(| \vec{a} \times \vec{b} | = 2\).

### Step 1: Understand the Expression
The expression \([ \vec{a} \, \vec{b} \, \vec{a} ]\) represents the scalar triple product of the vectors \(\vec{a}\), \(\vec{b}\), and \(\vec{a}\). The scalar triple product can be calculated using the formula:
\[ [\vec{u} \, \vec{v} \, \vec{w}] = \vec{u} \cdot (\vec{v} \times \vec{w}) \]
In our case, we can rewrite the expression as:
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