x∈[0,π/2]
2x∈[0,π]
2x+π/6∈[π/6,7π/6]
sin(2x+π/6)=(m-1)/2
当2x+π/6=π/2或2x+π/6∈(5π/6,7π/6]时仅有一解,得
m=3或m∈[0,2)