设y=f(x)=2arccosx,则x=cosy/2, y∈[0,2π]
∴其反函数为f-1(x)=cos x/2, x∈[0,2π]
方程f-1(x^2-π/3)=1/2就是
cos(x^2-π/3)/2=1/2
∴(x^2-π/3)/2=π/3,解得x=±√π
由f(x)=2arccosx =>x=cos(1/2*f(x)),即f-1(x)=cos(x/2),所以f-1(x^2-π/3)=cos[(x^2-π/3)/2]=1/2,最后有(x^2-π/3)/2=2kπ+π/6或(x^2-π/3)/2=2kπ-π/6,其中k∈N。最后的结果你就自己算啦~~~