设x=-2/3+(2/3+5/6)*(sint)^2 ,t∈[-π/2,π/2]此时：y=2√[(9/2)*(sint)^2]+3√[9*(cost)^2]=(6/√2)*sint+9*cost=3√11 *sin[t+arctan(3/√2)]当t=π/2-arctan(3/√2)时y取最大值3√11当t=arctan(3/√2)-π/2时y取...