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in the third step I have used the formula 2sinA cosA = sin2A in the fourth step, root 3 /2 is sin60, so I have rearranged to get the same use the formula sin( A+B) + Sin (A - B) = 2sin (A) cos(B) in step 5 in the penultimate step it should be 4cos40 cos20. typo error , sorry in the last step use 2cosA cos B = cos (A + B) + cos( A - B) answer is unchanged
please expln in detail
ReplyDeletein the third step I have used the formula 2sinA cosA = sin2A
ReplyDeletein the fourth step, root 3 /2 is sin60, so I have rearranged to get the same
use the formula sin( A+B) + Sin (A - B) = 2sin (A) cos(B) in step 5
in the penultimate step it should be 4cos40 cos20. typo error , sorry
in the last step use 2cosA cos B = cos (A + B) + cos( A - B)
answer is unchanged