x^2-(1+√3)x-√3=0
(x-1)(x-√3)=0
x1=1,x2=√3
1.tanA=1,A∈(0,π/2)
A=π/4
2.tanA=√3,A∈(0,π/2)
A=π/3
∴A=π/4或π/3