sin9A + 3sin7A + 3sin5A + sin3A = ( sin9A + sin3A ) + 3( sin7A + sin5A ) = 2sin6A.cos3A + 6sin6A.cosA = 2sin6A( cos3A + 3cosA ) = 2sin6A.4cosA_{3}
sin9A + 3sin7A + 3sin5A + sin3A = ( sin9A + sin3A ) + 3( sin7A + sin5A ) = 2sin6A.cos3A + 6sin6A.cosA = 2sin6A( cos3A + 3cosA ) = 2sin6A.4cosA^{3}