First, let's simplify the expression by using trigonometric identities:

11cos(287) - 25sin(557) = 11(cos(270+17)) - 25(sin(540+17))
= 11(-sin(17)) - 25(-sin(17))
= -11sin(17) + 25sin(17)
= 14sin(17)

Therefore, the expression simplifies to:

14sin(17) / sin(17) = 14

So, (11cos287-25sin557) / sin17 = 14.