plz send me the answer
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heya..!!!!
sinA + sin3A + sin5A + sin7A
=> (sinA + sin7A) + (sin3A + sin5A)
=> [ 2sin(7A + A)/2 × cos(7A - A)/2 ] + [ 2sin(5A + 3A)/2×cos(5A - 3A) ]
=> (2sin4A cos3A) + (2sin4A cosA)
=> 2sin4A(cos3A + cosA)
=> 2sin4A [ 2cos(3A + A)/2 × cos(3A - A)]
=> 2sin4A(2cos2A × cosA)
=> 4(sin4A×cos2A×cosA)
sinA + sin3A + sin5A + sin7A
=> (sinA + sin7A) + (sin3A + sin5A)
=> [ 2sin(7A + A)/2 × cos(7A - A)/2 ] + [ 2sin(5A + 3A)/2×cos(5A - 3A) ]
=> (2sin4A cos3A) + (2sin4A cosA)
=> 2sin4A(cos3A + cosA)
=> 2sin4A [ 2cos(3A + A)/2 × cos(3A - A)]
=> 2sin4A(2cos2A × cosA)
=> 4(sin4A×cos2A×cosA)
archana02:
thank you
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