tan(π-α)=1/2,则tanα=-1/2
tan2α=2tanα/(1-tan^2α)=-1/(1-1/4)=-4/3
sinβ=3/5,.β∈(π/2,π),
tanβ=3/4
则tan(2α-β)=(tan2α-tanβ)/(1+tan2αtanβ)=(-4/3-3/4)/(1+1)=-25/24
tan(π-α)=1/2,则tanα=-1/2
tan2α=2tanα/(1-tan^2α)=-1/(1-1/4)=-4/3
sinβ=3/5,.β∈(π/2,π),
tanβ=3/4
则tan(2α-β)=(tan2α-tanβ)/(1+tan2αtanβ)=(-4/3-3/4)/(1+1)=-25/24