①求ω的值：据根正弦函数求周期的公式：T=2π/ω,可知ω=2
②若x∈[0.π/2]且f（x）＝0,求x的值：若x∈[0.π/2],则ωx-π/4∈[-π/4.3π/4],而正弦在这个范围内等于0,说明ωx-π/4=0,故x= π/8