已知tana=-根号3/3 cosβ=根号3/2 αβ属于0-π
a=5π/6, β=π/6
1.tan(a+β) =tanπ=0
2.f(x)=sin(x+a)+cos(x+β)
=sin(x+5π/6)+cos(x+π/6)
=(√3+1)/2*(cosx-sinx)
=(√6+√2)/2*cos(x+π/4)
故对称轴方程是 x+π/4=2kπ
x=2kπ-π/4(k是整数）