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Cos1+cos2+cos3+...cos180=? Please give me the answer
Dear student As cos 179 = cos (180-1) = - cos1SimilarlyCos 178 = - cos2Cos 177 = - cos3 Hencw when adding all terms cancelled out.Only cos90 + cos180 is remaining Now cos 90 = 0 and cos 180 = - 1 Hence final answer is -1.
Dear student The given expression can be rearranged as:(Cos 1 + cos 179) + (cos2 + cos 178) + (cos3+ cos177) +…. + (cos89 + cos 91) + (cos90) + cos180But we know that: cos(180 - x)= - cos x, where x is angle in degree. So all the bracket totals except last 2 terms will be zero.So given expression is: 0 + (cos90) + ( cos180)= 0 + 0 + (-1)=-1.Answer: -1.
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