cos(π/7) + cos(6π/7) =几
cos(π/32)*cos(π/16)*cos(π/8)=
1:COS(-7π/12) =
cos(-19/6π)=?
cos(2派/7)+cos(4派/7)+cos(6派/7)=?
求证cos2π/7+cosπ/3=cosπ/7+cos3π/7
cos(-19/6π)
已知cos(π/6+a)=根号3/3,求cos(7π/6+a)的值
①化简[sin(2π+α)*cos(7π-α)]/cos(-α)②已知cosθ=-3/5,θ∈(π/2,π),求sin(
若函数f(x)=[2cos^3 x-sin^2 (x+π)-2cos (-x-π)+1]/[2+2cos^2(7π+x)
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
已知cosα=1/7,cos(α+β)=-11/14,且α、β∈(0,2/Π),求cosβ的值