解析:原式=-sin1 200°cos1 290°-cos1 020°·sin1 050°+tan945°
=-sin(-60°+7×180°)·cos(30°+7×180°)-cos(-60°+3×360°)·sin(-30°+3×360°)+tan(45°+5×180°)=sin(-60°)(-cos30°)-cos(-60°)sin(-30°)+tan45°
=×()-×(-)+1=2.
答案:2
9.已知cos(11π-3)=p,用p表示tan(-3)=______________.
解析:∵cos(11π-3)=-cos(-3)=-cos3=p,
∴cos3=-p.又<3<π,
∴sin3=.
∴tan(-3)=-tan3=
答案:
10.=,则cos(3π-θ)=____________.
解析:∵,
∴cosθ=.∴cos(3π-θ)=cos(π-θ)=-cosθ=.
答案:
综合运用
11.已知sin(-α)=,则cos(+α)=____________.
解析:∵(-α)+(+α)=,
∴cos(+α)=cos[-(-α)]=sin(-α)=.
答案:
12.(2006山东滨州模拟) 已知函数f(x)=asin(πx+α)+bcos(πx+β),其中a,b,α,β都是非零实数,且满足f(2 005)=-1,则f(2 006)等于( )
A.-1 B.0 C.1 D.2
解析:由已知,f(2 005)=asin(2 005π+α)+bcos(2 005π+β)=asin(π+α)+bcos(π+β)=-asinα-bcosβ=-1,
∴asinα+bcosβ=1,而f(2 006)=asin(2 006π+α)+bcos(2 006π+β)=asinα+bcosβ=1.
答案:C