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What is the value of cos(A + B) + cos (A – B) ? (A) 2 sin A cos B (B) 2 cos A sin B (C) 2 cos A cos B (D) 2 sin A sin B. |
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Answer» The correct option is (C) 2 cos A cos B Explanation: cos (A + B) + cos (A – B) ⇒ cosAcosB – sinAsinB + cosAcosB + sinAsinB ⇒ 2cosAcosB |
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