tan(π+α)=3 则 sin(π+α)cos(π-α)=?知道答案是-(3/10)

已知α,β∈(0,π/2),且2tanα+3sinβ=7,tanα-6sinβ=1,则sinα= 已知tanα=3tan(α+β),β=π/6,则sin(2α-β)的值 tanα=m,则sin(α+3π)+cos(π+α)/sin(－α)-cos(π+α)等于? tanα=2,求sin(π-α)cos(2π-α)sin(-α+ 3π/2)/tan(-α-π)sin(-π-α)的值 若a属于(0,π/2)试比较tanα、tan(tanα)、tan(sinα) tanα=3,则sinα-cosα/2sinα+cosα等于多少-π/12等于多少 若sin (π/4+α)sin(π/4-α)=-1/8,则2sin²α+tanα-1/tanα-1的值为 已知α∈(0,π|2）,2tanα+3sinβ=7,且tanα-6sinβ=1,求sinα的值 若tan(π+α)=-a则sin(-3π-α)×cos(7π+α)= 1.求证tanαsinα/tanα-sinα=tanα+sinα/tanαsinα2.已知sinα+cosα=-1/5(π/2 问几道高中三角函数题1、求证：tanα*sinα/(tanα-sinα)=(tanα+sinα)/tanα*sinα2、已知sinθ+cosθ=1/5,θ∈(0,π),求（1）sinθ-cosθ；（2）tanθ3、若α角的终边落在第三或第四象限,则α/2的终边落在第______ sin(π-α)=-2/3 α∈（-π/2,0） 则tanα等于 tan(α+π/4)=2,则cos2α+3sin^2α+tan2α=? 若tanα=m 则sin(-5π-α)cos(3x+α）= tan(π/4-α)=-1/3 则sin(2α+π/4)的值 tan(π/4-α)=-1/3 则sin(2α+π/4)的值为? 若sin(α-π)=3/5,α为第四象限角,则tanα等于 已知tan(π+α)=3,则2cos(π-α)-3sin(π+α)/4sin(α+π/2)+sin(2π-α)=