acosC+√3asinC-b-c=0
sinAcosC+√3sinAsinC-sinB-sinC=0
sinAcosC+√3sinAsinC-sinAcosC-sinCcosA-sinC=0
√3sinAsinC-sinCcosA-sinC=0
√3sinA-cosA-1=0
2sin(A-π/6)=1
A-π/6=π/6 a=π/3 A-π/6=5π/6 A=π（不符题意）
S=√3=1/2bcsinA bc=4
cosA=(b^2+c^2-a^2)/2bc
(b+c)^2-2bc=2*4*1/2-2^2=0
(b+c)^2=8 无解