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Comparing imaginary parts in the expansion of (cos x + i sin x)^2 gives sin 2x equal to what?
Asin x + cos x
Bsin^2 x − cos^2 x
C2 sin x cos x
D2 sin^2 x cos x
Answer & Solution
Correct answer: C. 2 sin x cos x
The imaginary part of the expansion is 2 sin x cos x, which equals sin 2x.
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