高考数学题不会~ 请教详细解答

-π/12<=x<=π/2 -π/3<=2x-π/6<=5π/6 令t=2x-π/6 t∈[-π/3,5π/6] t=2x-π/6=-π/3时ymin=-√3/2 t=2x-π/6=π/2时ymax=1 所以函数值域[-√3/2,1] 把2x-π/6看做X X∈[-π/3,5π/6] X=-π/3