求值:=________.
(2010·全国卷Ⅰ理,14)已知α为第三象限角,cos2α=-,则tan(
+2α)=____________.
已知sin=
,则sin
=______.
(2010·重庆南开中学)已知2tanα·sinα=3,- <α<0,则cos
的值是( )
A.0 B. C.1 D.
已知α、β为锐角,且tanα=,tanβ=
,则sin(α+β)=________.
若cos(α+β)cosα+sin(α+β)sinα=-,且450°<β<540°,则sin(60°-β)=________.