復(fù)合函數(shù)sin平方的導(dǎo)數(shù)是sin2x或者寫成2sinxcosx也可以，因?yàn)檫@個(gè)復(fù)合函數(shù)的母函數(shù)是u^2，子函數(shù)是sinx，根據(jù)復(fù)合函數(shù)的求導(dǎo)法則知，復(fù)合函數(shù)的導(dǎo)數(shù)應(yīng)該等于母函數(shù)的導(dǎo)數(shù)乘以子函數(shù)的導(dǎo)數(shù)，因此該復(fù)合函數(shù)的導(dǎo)數(shù)等于 [(sinx)^2]' =(u^2)'*(sinx)' =2u*cosx =2sinxcosx =sin2x...