化简cos(x+y)sinx-sin(x+y)cosx

问题描述:

化简cos(x+y)sinx-sin(x+y)cosx

原式=sin[x-(x+y)]=sin-y=-siny

cos(x+y)sinx-sin(x+y)cosx
=sin[x-(x+y)]
=sin(-y)
=-siny