已知cos(x-y/2)=-1/9,sin(x/2-y)=2/3,0_数学解答

已知cos(x-y/2)=-1/9,sin(x/2-y)=2/3,0

人气：494 ℃　时间：2020-04-09 19:49:52

解答

y=cosx/(2cosx+1)
=(2cosx+1)y=cosx
=2ycosx+y=cosx
y=(1-2y)cosx
y=1/2时
0=1/2
y不等于1/2