1.已知cos(3π/4 +a)=-1/3,求cos(π/4 -a)2.已知tan(2π/3 +a)=√3/4,求tan(5π/3 -a)已知cos(3π/4 +a)=-1/3,求cos(π/4 -a) 2. 已知tan(2π/3 +a)=√3/4,求tan(5π/3 -a)

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1.已知cos(3π/4+a)=-1/3,求cos(π/4-a)2.已知tan(2π/3+a)=√3/4,求tan(5π/3-a)已知cos(3π/4+a)=-1/3,求cos(π/4-a)2.已知t

1.已知cos(3π/4 +a)=-1/3,求cos(π/4 -a)2.已知tan(2π/3 +a)=√3/4,求tan(5π/3 -a)已知cos(3π/4 +a)=-1/3,求cos(π/4 -a) 2. 已知tan(2π/3 +a)=√3/4,求tan(5π/3 -a)
1.已知cos(3π/4 +a)=-1/3,求cos(π/4 -a)2.已知tan(2π/3 +a)=√3/4,求tan(5π/3 -a)

  1. 已知cos(3π/4 +a)=-1/3,求cos(π/4 -a)

   2.  已知tan(2π/3 +a)=√3/4,求tan(5π/3 -a)

1.已知cos(3π/4 +a)=-1/3,求cos(π/4 -a)2.已知tan(2π/3 +a)=√3/4,求tan(5π/3 -a)已知cos(3π/4 +a)=-1/3,求cos(π/4 -a) 2. 已知tan(2π/3 +a)=√3/4,求tan(5π/3 -a)

cos(π/4 -a)=cos(-π/4 +a)

                            =-cos(-π/4 +a+π)
                            =-1/3
2.tan(5π/3 -a)=-tan(-5π/3+a)
                                =-tan(4π/3+a)=-tan(2π/3+2π/3+a)
                                =-(-√3+√3/4)/(1+√3*√3/4)
                               =3√3/7