sin2A+√3cos2A=2sin2B2(1/2sin2A+√3/2cos2A)=sin2Bsin(2A+π/3)=sin2B 2A+π/3=π-2B ,,或 2A+π/3=2B A+B=π/3 , ,或 B-A=π/6 A+B=π/3C=2π/3
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