已知α为第二象限角，f(α)＝sin(α−π2)cos(3π2+α)tan(π−α)tan(−α−π)sin(−α−π)

已知α为第二象限角，f(α)＝sin(α−π2)cos(3π2+α)tan(π−α)tan(−α−π)sin(−α−π) 已知α是第二象限角，f（α）=sin(π−α)tan(−α−π)sin(π+α)cos(2π−α)tan(−α)． 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α是第三象限角,且f(α)=[sin(π+α)cos(2π-α)tan(-α+3π/2)tan(-α-π)]/sin 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 1.已知α是第二象限角,f(α)=[sin(3π/2-α)·cos(2π-α)·tan(π-α)]/-cos(-π-α) 已知α是第三象限角,f(α)=[sin(π-a)cos(2π-a)tan(1.5π-a)tan(-a-π)]/sin(- α是第三象限角,f(α)={sin（α-π/2）cos（3π/2+α）tan（π-α）}/{tan（-α-π）sin（- 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 已知α是第三象限的角，且f（α）=sin(π−α)cos(2π−α)tan(3π2−α)cos(−π−α)． 已知f(α)＝sin(π−α)•cos(2π−α)•tan(−π−α)sin(−π−α) 已知tanα=2，求sinα−3cosαsinα+cosα