已知f(α)=(sin(Π／2-α)cos(2Π-α)tan(-α+3Π))／(tan(Π+α)sin(Π／2＋α)),

已知f(α)=sin（π-α）cos(2π-α)tan(-α+3π/2)tan(-α-π) ／sin(-π-α).(1) ②若cos（已知α是第三象限角f(α)=sin(π-α)cos(2π-α)tan(-α-π)/tan（-α）sin（-π 已知α是第三象限角,且f(α)=[sin(π+α)cos(2π-α)tan(-α+3π/2)tan(-α-π)]/sin 已知α为第三象限角,且f(α)=sin(π-α)cos(2π-α)tan(-α+π)/sin(π+α)tan(2π-α) 已知f(α)=sin(π-α)cos(2π-α)tan(π-α)/-tan(-π-α)sin(-π-α),若α是第三象限 有关三角函数的题已知f(α)=sin(π-α)cos(2π-α)tan(-α+π)/-tan(-α-π)sin(-π-α 1.已知cos(π/6-α)=1/3,求sin(2/3π-α) 2.求证tan^2α-sin^2α=tan^2α-sin 高一数学急!已知f(a)=sin^2(π-α)·cos(2π-α)·tan(-π+α)/sin(-π+α)·tan(-α 化简：[sin(π+α)*cos(π-α)*tan(π-α)]/[cos(π/2+α)*tan(3π/2-α)*tan( 已知tan(α+π/4)=2,则(2sinα+cosα)/(3cosα-2sinα) 已知tan(α+π/4)=2,求2cosα-sinα/cosα+3sinα 已知tan（α+π/4）=3,求cosα+2sinα/cosα-sinα的值