1.sinA=√(1-cos²A)=3/5sinC=sin(180°-A-B)=sinAcosB+sinBcosA=(3+4√3)/102.正弦定理a/sinA=b/sinBa=bsinA/sinB=6/5S△ABC=(1/2)absinC=(1/2)*(6/5)*(√3)*(3+4√3)/10=9(1+√3)/50