最大值是根号3
S=√3(a^2+b^2-c^2)/4=√3/2abcosC=1/2absinC , √3cosC=sinC, tanC=√3 ,C=π/3a^2+b^2-c^2=2abcosCsinA+sinB=sin(π-π/3-B)+sinB=sin(2π/3-B)+sinB=√3/2cosB-1/2sinB+sinB=√3/2cosB+1/2sinB=sin(B+π/3)sinA+sinB的最大值=1
