已知函数f(x)=sin(x+π/6)+sin(x-π/6)+cosx+a(a属于R,a是常数)

1、
f(x)=sinxcosπ/6+cosxsinπ/6+sinxcosπ/6-cosxsinπ/6+cosx+a
=2sinxcosπ/6+cosx+a
=√3sinx+cosx+a
=√[(√3)²+1²]sin(x+z)+a
=2sin(x+z)+a
其中tanz=1/√3
所以T=2π/1=2π
2、
tanz=1/√3
z=π/6
f(x)=2sin(x+π/6)+a
-π/2