tan=-2,且cosθ＞0,则sin= .——青夏教育精英家教网——

tan(5π+θ)=-2,且cosθ＞0,则sin(-π+θ)=________________.

已知tan(π+α)=3,则=__________________.

设f(x)=asin(πx+α)+bcos(πx+β)+4(a、b、α、β是常数)且f(2 004)=5,则f(2 005)等于( )

A.1 B.3 C.5 D.7

若cos(-100°)=a,则tan80°等于( )

A.- B.C.- D.

化简的结果是( )

A.cos110° B.cos70° C.sin70° D.cos20°

下列等式中,正确的是( )

A.sin(-α-π)=sinα B.sin(π-α)=-sin(-α-π)

C.cos(-α+β)=-cos(α-β) D.cos(-α+β)=cos(α+β)

sin(π-α)+sin(2π-α)+sin(3π-α)+sin(4π-α)=______________.

(1)sin(-1 200°)=____________________;

(2)cos=____________________.

设A、B、C分别为△ABC的三个内角,则正确的结论是( )

A.sin(B+C)=sinA B.cos(B+C)=cosA

C.tan(B+C)=tanA D.cot(B+C)=cotA

若cos(π-α)=-,＜α＜2π,则sin(2π-α)等于( )

A.B.±C.D.-

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