alleryStart learning →Adding the expansions of cos(A+B) and cos(A−B) yields the product
A2 cosA cosB
B2 sinA sinB
C2 sinA cosB
DcosA cosB
Answer & Solution
Correct answer: A. 2 cosA cosB
Adding the two cosine expansions cancels the sine products and leaves 2 cosA cosB.
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