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Cos20•cos40•cos60•cos80=1/16 |
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Answer» In place of 60 +30 I have mistaken i-e:(60+20) @= 20 Use: cos @× cos ([email\xa0protected])×cos ([email\xa0protected]) =cos [email\xa0protected]/4and cos 60= 1/2 Therefore cos 20.cos40.cos60.cos80=cos 20 cos (60-20) cos (60+30) cos60= cos 60.cos60/4= 1/2×1/2×1/4=1/16 |
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