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Evaluate the product cos A * cos(60deg - A) * cos(60deg + A) and express it as a single multiple-angle term.

1. (1/4) cos 3A
2. (1/2) cos 3A
3. (1/4) sin 3A
4. cos 3A

Correct answer: (1/4) cos 3A

Solution

The product simplifies to (1/4)(4 cos³ A - 3 cos A) = (1/4) cos 3A.

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