1.代入:f（π/3）=2分之根号3a+b/2
f（π/2）=a+0=1
得:a=1 b=-根号3
2.f（x）=sinx-根号3cosx
=2sin(x-π/3)
当sin(x-π/3)=1时,即x-π/3=π/2+2kπ时,f（x）取得最大值
此时x=5π/6+2kπ
可能计算错了,但方法是这样~