$\"\"$

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The vector is $\"\"$ .

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Direction angle of a vector $\"\"$ is $\"\"$ .

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Compare the vector $\"\"$ with $\"\"$ .

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$\"\"$ and $\"\"$ .

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Direction angle: $\"\"$ .

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$\"\"$

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The angle is $\"\"$ .

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$\"\"$

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The direction angle is $\"\"$ .