$\"\"$

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$\"\"$ .

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The vectors are $\"\"$ , $\"\"$ and $\"\"$ .

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Apply dot product formula: $\"\"$ .

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$\"\"$ (Substitute : $\"\"$ )

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$ $\"\"$

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The result of $\"\"$ and the result is a "vector".