Math, asked by selvakumar99, 1 year ago

prove that cosA+cos(120-A)+cos(120+A)=0

Answers

Answered by ankitarya2301
8
Hope the solution helps.
Attachments:
Answered by sandy1816
5

Answer:

CosA+cos(120+A)+cos(120-A)

=CosA+2cos120cosA

[cos(A+B)+cos(A-B)=2cosAcosB]

=cosA+2cos(180-60)cosA

=CosA-2cos60cosA

=cosA-2(1/2)cosA

=cosA-cosA

=0

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