y=-sin(x/2)*[1-2（cos(x/4)^2)]的导数

y=-sin(x/2)*[1-2（cos(x/4)^2)]的导数
y=-sin(x/2)*[1-2（cos(x/4)^2)]的导数

y=-sin(x/2)*[1-2（cos(x/4)^2)]的导数
=-sin(x/2)*（-cos（x/2））
=0.5sinx
∴y‘=0.5cosx

y= - sin(x/2)* [1-2（cos(x/4)^2)] = sin(x/2) cos(x/2) = (1/2) sinx
y ' = (1/2)cosx

=-sin(x/2)*（-cos（x/2））
=0.5sinx
∴y‘=0.5cosx 就是这个过程啊，先化简式子，再进行求导！！！！

y= - sin(x/2)* [1-2（cos(x/4)^2)] = sin(x/2) cos(x/2) = 0.5sinx
y ' = 0.5cosx