课时知能训练
一、选择题
1.3-sin 70°2-cos210°=( )
A.12 B.22 C.2 D.32
2.设tan(α+β)=25,tan(β-π4)=14,则tan (α+π4)的值是( )
A.318 B.322 C.1318 D.1322
3.(2012•济南模拟)若cos α=-45,α是第三象限的角,则sin(α+π4)等于( )
A.-7210 B.7210 C.-210 D.210
4.已知cos(α-π6)+sin α=453,则sin(α+76π)的值是( )
A.-235 B.235 C.-45 D.45
5.(2011•浙江高考)若0<α<π2,-π2<β<0,cos(π4+α)=13,cos(π4-β2)=33,则cos(α+β2)=( )
A.33 B.-33 C.539 D.-69