1.∵cos(x+m)=cosm cosx-sinm sinx=√3/2cosx+1/2sinx
∴cosm=√3/2,sinm= -1/2
∴m=2kπ+5π/6 ,其中看∈Z
2.∵tan(A-B)=(tanA-tanB)/(1+tanAtanB)
令A=x+π/4 ,B=π/4
得tanx=[tan(x+π/4)-tanπ/4]/[1+tan(x+π/4)tanπ/4]
=（1/2-1）/（1+1/2 ×1）
= -1/3