If `veca,vecbandvecc` are unit vectors such that `veca+vecb+vecc=0`, then the value of `veca.vecb+vecb.vecc+vecc.veca` is

Explanation

To solve the problem, we need to find the value of \( \vec{a} \cdot \vec{b} + \vec{b} \cdot \vec{c} + \vec{c} \cdot \vec{a} \) given that \( \vec{a} + \vec{b} + \vec{c} = 0 \) and that \( \vec{a}, \vec{b}, \vec{c} \) are unit vectors.

### Step 1: Use the given equation
We start with the equation:
\[ \vec{a} + \vec{b} + \vec{c} = 0 \]
From this, we can express \( \vec{c} \) in terms of \( \vec{a} \) and \( \vec{b} \):
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