Question

sina/2*sin7a/2+sin3a/2*sin11a/2=sin2a*sin5a
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Answer 1

Answer:

LHS = sin(A/2).sin(7A/2) + sin(3A/2)sin(11A/2)

={2sin(A/2).sin(7A/2) + 2sin(3A/2)sin(11A/2)}/2

={cos(7A/2-A/2)-cos(7A/2+A/2)+cos(11A/2-3A/2)-cos(3A/2+11A/2)}/2

={cos(3A) - cos(4A) + cos(4A) - cos(7A)}/2

={cos(3A) - cos(7A)}/2

=2sin(5A)sin(2A)/2

=sin(2A).sin(5A) = RHS

Step-by-step explanation:

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