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化简(tan-150ºcos-210ºcos-390º)/sin-1050º

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解决时间 2021-07-21 02:03
  • 提问者网友:了了无期
  • 2021-07-20 14:58

(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)

最佳答案
  • 五星知识达人网友:長槍戰八方
  • 2021-07-20 15:13

(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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