题中sinA=3根号3肯定错误
cosA=根号[1-(sinA)^2]＝根号6/3
sinB=sin(90°-A)=cosA=根号6/3
tanA=sinA/cosA=(根号3/3)/(根号6/3)=根号2/2
根据正弦定理
BC/sinA=AC/sinB=AB/sinC=k
AC=ksinB
AB=ksin90°=k
因为AC+BA=3根号2+2根号3
ksinB+k=3根号2+2根号3
k=3根号3
BC/sinA=3根号3
BC=根号6.