y= sinX*cosX 求导。

2024-11-06 06:33:09
推荐回答(2个)
回答(1):

(sinxcosx)′
=(sinx) ′cosx+sinx(cosx) ′
=cosxcosx+sinx(-sinx)
=(cosx)^2-(sinx)^2
=cos2x
求导法则:f(x)g(x)=f′(x)g(x)+f(x)g′(x)

回答(2):

(sinxcosx)′
=(sinx) ′cosx+sinx(cosx) ′
=cosxcosx+sinx(-sinx)
=(cosx)^2-(sinx)^2
=cos2x
f(x)g(x)=f′(x)g(x)+f(x)g′(x)
或者先用倍角公式sin2α=2sinα*cosα化简
(sinxcosx)′
=(1/2sin2x)′
=1/2cos2x*2
=cos2x