若cos α＋2sin α＝－，则tan α＝(　　)

A.                                                         B．2

C．－                                                   D．－2

已知sin(3π＋α)＝2sin，求下列各式的值：

(1) ；(2)sin²α＋sin 2α.

求值：sin(－1 200°)·cos 1 290°＋cos(－1 020°)·sin(－1 050°)＋tan 945°.　

＝________.

化简＝________.   

已知sin(π－α)＝log₈，且α∈，则tan(2π－α)的值为________．

已知f(α)＝，则f 的值为(　　)

A.                                                         B．－

C．－                                                   D.

已知α为锐角，且2tan(π－α)－3cos＋5＝0，tan(π＋α)＋6sin(π＋β)＝1，则sin α的值是(　　)

A.                                                    B.

C.                                                   D.

已知则tan φ＝(　　)

A．－                                                B.

C．－                                                 D.

若＝(　　)

A．sin θ－cos θ                                        B．cos θ－sin θ

C．±(sin θ－cos θ)                                    D．sin θ＋cos θ