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The value of cos 27° +cos 93°+cos 147 is |
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Answer» ONG>ANSWER: cos27°+cos93°+cos147° =2cos(27°+93°)/2cos(27°-93°)/2+cos147° =2cos60°cos33°+cos(180°-33°) =2×1/2cos33°+cos{(90°×2)-33°} [∵, cos60°=1/2 and cos(180°-Ф)=-cosФ] =cos33°+(-cos33°) =cos33°-cos33° =0 (PROVED) |
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