sina+√3cosa
=2(1/2sina+√3/2cosa)
=2(sinacos60°+cosasin60°)
=2sin(a+60°)
∵-1≤sin(a+60°)≤1
∴-2≤sin(a+60°≤2
∴-2≤（2m+1)/(3-m)≤2
1、3-m>0,m3
∴m≤5/4或m>3