(1)化简(tan-150ºcos-210ºcos-390º)/sin-1050º
(2)求cos-1020º·sin-1050º+tan945º的值
(3)已知sin(π-α)-cos(π+α)=√2/4,sin(π+α)+cos(3π-α)的值
(4)已知sin(x+π/6)=1/3,求sin(7π/6+x)+ cos^2(5π/6-x)
(5)设tan(5π+α)=m,求(sin(α-3π)+cos(π-α))/(sin(-α)+cos(π+α))的值
(6)已知cos(π/6-α)=√3/3,求cos(5π/6+α)-sin^2(α-5π/6)
(1)(tan-150ºcos-210ºcos-390º)/sin-1050º
=[tan30º*(-cos30º)*cos30º]/sin30º
=-cos30º
=-根号3/2
(2)cos-1020º·sin-1050º+tan945º
=cos60º·sin30º+tan45º
=1.25
(3)sin(π-α)-cos(π+α)
=sinα+cosα
=√2/4
sin(π+α)+cos(3π-α)
=-sinα-cosα
=-√2/4
(4)sin(x+π/6)=1/3,
sin(7π/6+x)+ cos^2(5π/6-x)
=-sin(x+π/6)+cos^2(π/6+x)
=-sin(x+π/6)+1-sin^2(π/6+x)
=-1/3+1-1/9
=5/9
(5)tan(5π+α)=tanα=m,
(sin(α-3π)+cos(π-α))/(sin(-α)+cos(π+α))
=(-sinα-cosα)/(-sinα-cosα)
=1
(6)有点麻烦,如果不是你抄错数的话,那么就要展开cos(π/6-α)=√3/3,然后和sin^2α+cos^2α=1联立,解得sinα和cosα,然后再代入下式来解
cos(5π/6+α)-sin^2(α-5π/6)
=-cos(π/6-α)-[-sin(α+π/6)]^2
=-√3/3-[sinαcos30°+cosαsin30°]^2
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