tanA+tanB+根号3=根号3tanA*tanB
tanA+tanB=根号3(tanA*tanB-1)
(tanA+tanB)/(1-tanAtanB)=-根号3=tan(A+B)
A+B∈(0,π)
A+B=120°
所以∠c=180-120=60°
a=4,b+c=5
根据余弦定理有
c^2=a^2+b^2-2abcos60,c=5-b
解得:b=3/2
S=1/2absinC=3√3/2
tanA+tanB+根号3=根号3tanA*tanB
tanA+tanB=根号3(tanA*tanB-1)
(tanA+tanB)/(1-tanAtanB)=-根号3=tan(A+B)
A+B∈(0,π)
A+B=120°
所以∠c=180-120=60°
a=4,b+c=5
根据余弦定理有
c^2=a^2+b^2-2abcos60,c=5-b
解得:b=3/2
S=1/2absinC=3√3/2