lim(cosx-1)/x,x趋于0,怎么化简成-sinx?

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lim(cosx-1)/x,x趋于0,怎么化简成-sinx?
lim(cosx-1)/x,x趋于0,怎么化简成-sinx?

lim(cosx-1)/x,x趋于0,怎么化简成-sinx?
lim【x→0】(cosx-1)/x
=lim【x→0】(-x²/2)/x
=lim【x→0】-x/2
=0

cosx-1=1-2sin²(x/2)-1=-2sin²(x/2)
lim(cosx-1)/x=lim[-2sin²(x/2)]/(x/2) *(1/2)=lim[-sin(x/2)]=0