因为2*向量AB*向量AC=√3*|AB|*|AC|
向量AB*向量AC=|AB|*|AC|*cosA
故：cosA=√3/2
故：A=π/6
因为√3*|AB|*|AC|=3*BC²＝3*|BC|²
由a/sinA=b/ainB=c/sinC=2R可知：
故：√3*sinC*sinB=3sin²A=3/4
故：sinC*sin（5π/6-C）=√3/4
故：1/2* [cos(2C-5π/6)+cos(5π/6)] =√3/4
故：cos(2C-5π/6)= √3/2
故：2C-5π/6=π/6或2C-5π/6=-π/6
故：C=π/2或C=π/3
对应的B=π/3或B=π/2