$\"\"$

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The complex number is $\"\"$ .

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De Moivres Theorem :

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$\"\"$ is a complex number then $\"\"$ where $\"\"$ is a positive integer.

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$\"\"$ .

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Apply De Moivres theorem.

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$\"\"$

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$\"\"$ .

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$\"\"$ .

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$\"\"$

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$\"\"$ .