由正弦定理:b/sinB=2R√3/(√3/2)=2R2R=2{a=2sinA{c=2sinCc+2a=2sinC+4sinA=2sinA+4sin(120º-A)c+2a=2sinA+4[(√3/2)cosA+(1/2)sinA]=4sinA+2√3cosA=√28[(4/√28)sinA+(2√3/√28)cosA]=√28sin[A+φ](其中cosφ=(4/√28),sinφ=(2√3/√28))当A+φ=π/2时,c+2a取最值√28