答案：∠A=30°
上式=1/2
∵b^2 +c^2 =a^2+√3bc
∴b^2+c^2-a^2=√3bc
∴cosA=(b^2+c^2-a^2)/2bc=√3bc/2bc=√3/2
∴A=30°
2sinBcos-sin(B-C)
=2sinBcosC-sinBcosC+sinCcosB
=sinBcosC+sinCcosB
=sin(B+C)
=sinA
=1/2
呼呼,累死了.厄,懂了吗?