y = x - sin(x/2)cos(x/2)y'=1-cos(x/2)*(1/2)*cos(x/2)+sin(x/2)*(-sinx/2)*(1/2)=1-1/2 [cos²x/2-sin²x/2]=1-1/2cosx如果满意，请采纳，谢谢
y=x-sinx/2所以y'=1-cosx/2
