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Which identity for sin 3θ follows from expanding (cos θ + i sin θ)³?
A3 sin θ − 4 sin³θ
B4 sin θ − 3 sin³θ
C3 sin θ cos θ
D3 sin θ + 4 sin³θ
Answer & Solution
Correct answer: A. 3 sin θ − 4 sin³θ
The imaginary part is 3cos²θ sin θ − sin³θ, which simplifies to 3 sin θ − 4 sin³θ.
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