alleryStart learning →The expansion of cos(A + B) for any angles A and B is
AcosA cosB + sinA sinB
BsinA sinB − cosA cosB
CsinA cosB − cosA sinB
DcosA cosB − sinA sinB
Answer & Solution
Correct answer: D. cosA cosB − sinA sinB
Replacing B by −B in the cos(A − B) formula flips the sign of the sine product, giving cosA cosB − sinA sinB.
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