√3a = 2c sinA
√3/2 a/c = sinA
√3/2 sinA/sinC = sinA
sinC = √3/2
C = π/3,或2π/3
a=3
S=3√3/2
S=1/2absinC
b=2S/(asinC)=2*3√3/2 /(3*√3/2)=2
c=√{a^2+b^2-2abcosC) = √(3^2+2^2±2*2*3*1/2) = √(13±6)=√7,或√19考试题阿对不对？？没问题