Which expression is equivalent to sin(84°)cos(43°) + cos(84°)sin(43°)?

Use the sine addition identity: sin(a)cos(b) + cos(a)sin(b) = sin(a + b). With a = 84° and b = 43°, the expression equals sin(84° + 43°) = sin(127°). Therefore, the equivalent expression is sin(127°), choice C.

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