已知cos(α-6/π)=12/13,π/6
已知cos(α-π6
已知α为锐角,且cos(α+π/6)=5/13,求cosα的值
已知cos(π6+α)=33
已知cos(a+π6
已知cos(π/6-α)=根号3/3,求cos(5π/6+α)的值
已知(sinα-cosα)/(sinα+cosα)=1/3,则cos^4(π/3+α)-cos^4(π/6-α)的值为
已知α为锐角,且cos(α+π6)=45,则cosα的值为( )
已知cos(13π/6+x)=根3/3,求cos(23π/6-x)的值
已知cos(θ+π/6)=5/13,0
已知cos(π/6-a)=根号3/3,求cos(5π/6+a)-cos²(π/3+a)
已知cos(x-π/6)=-根号三分之三 则cos(x)+cos(x-π/3)的值是
1.已知cosα=12/13,α∈(3π/2,2π),求cos(α+π/4).