三角代换 由于(√(x-3))^2+(√(4-x))^2=1 设√(x-3)=cosθ √(4-x)=sinθ θ∈[0,π/2] y=√(x-3)+√(12-3x) =cosθ+√3sinθ =2[(1/2)cosθ+(√3/2)sinθ] =2sin(θ+π/6) 由0≤θ≤π/2 则π/6≤θ+π/6≤2π/3 1/...