(1)1/tanA+1/tanC=(tanA+tanC)/(tanA*tanC)=cosA*cosC(tanA+tanC)/(sinA*sinC)
=(sinAcosC+sinCcosA)/(sinA*sinC)=[sin(A+C)]/(sinA*sinC)
∵cosB=3/4 又∵在△ABC中,00 ∴a+c=3
(1)1/tanA+1/tanC=(tanA+tanC)/(tanA*tanC)=cosA*cosC(tanA+tanC)/(sinA*sinC)
=(sinAcosC+sinCcosA)/(sinA*sinC)=[sin(A+C)]/(sinA*sinC)
∵cosB=3/4 又∵在△ABC中,00 ∴a+c=3