lim(1-(cosx)^3)/(x*sin2x)怎么做?

问题描述:

lim(1-(cosx)^3)/(x*sin2x)怎么做?

lim(1-(cosx)^3)/(x*sin2x)
=lim(1-cosx)(1+cosx+cos²x)/(2x²)
=3/2lim(1-cosx)/(x²)
=3/2lim(x²/2)/(x²)
=3/2×1/2
=3/4