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For real x and integer n, (cos x + i sin x)^n is equal to which expression?
Acos nx + i sin nx
Bcos nx − i sin nx
Cn cos x + i n sin x
Dcos^n x + i sin^n x
Answer & Solution
Correct answer: A. cos nx + i sin nx
De Moivre's theorem states that raising cos x + i sin x to an integer power n multiplies the angle by n.
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