COS 1 DEGREE + COS 2 DEGREE + COS 3 DEGREE +......COS 180 DEGREE =?

Asked by Vivek Sehgal | 2nd May, 2012, 01:20: PM

Expert Answer:

cos1 + cos2 + cos3 +....+cos180
= cos(180-179) + cos(180-178) +.... + cos(180-91) + cos90 + cos91 + cos92 +... + cos179+ cos180
 
= -cos179 -cos178-...-cos91 + cos90 + cos91 +.... cos179 + cos180
 
= cos90 + cos180
 
= -1 Ans

Answered by  | 2nd May, 2012, 10:24: PM

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