不好写,极限符号就不写了:
(tanx-sinx)/sin³x
=(1-cosx)/[cosxsin²x]
=(1-cosx)/[cosx(1-cos²x)]
=(1-cosx)/[cosx(1-cosx)(1+cosx)]
=1/[cosx(1+cosx)]
下面直接把cosx=1带入
不好写,极限符号就不写了:
(tanx-sinx)/sin³x
=(1-cosx)/[cosxsin²x]
=(1-cosx)/[cosx(1-cos²x)]
=(1-cosx)/[cosx(1-cosx)(1+cosx)]
=1/[cosx(1+cosx)]
下面直接把cosx=1带入