x=π/6是对称轴,左加右减原则,y=asinx-bcosx向左平移π/2单位,y=asin(x+π/2)-bcos(x+π/2)=acosx+bsinx,π/6-π/2=-π/3 对称轴有无数条,由于sin为x,所以对称轴是X=-π/3 +kπ解法2：y=asinx-bcosx可变为y=根号a2+b...