Position vectors of the points A,B,C,D are

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$\"\"$

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Since A,B,C,D are coplanar

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$\"\"$

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Now $\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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Now $\"\"$

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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 value of n is $\"\"$ .