math problem--limit

lim h→0 { [sin (π+h) - sin(π)] / h}

Let f(x) = sin x
The above expression can be expressed as:

lim h -> 0 { [ f(x + h) - f(x) ] / h }

You see, it's just to find d/dx (sin x) |x = π

so the answer is cosπ = -1

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