答：B=π/3,则A+C=2π/3sin2A+sin(A-C)-sinB=0sin2A+sin(2A-2π/3)=sinπ/3sin2A-(1/2)sin2A-(√3/2)cos2A=sinπ/3sin(2A-π/3)=sinπ/3因为：三角形ABC是锐角三角形所以：2A-π/3=π/3,A=π/3所以：A=B=C=π/3所以...sin2A+sin(2A-2π/3)=sinπ/3sin2A-(1/2)sin2A-(√3/2)cos2A=sinπ/3怎么转换的利用公式：sin(a-b)=sinacosb-cosasinbsin(2A-2π/3)=sin2Acos2π/3-cos2Asin2π/3=-(1/2)sin2A-(√3/2)cos2A