函数y=sin(ωx+φ)(ω>0,|φ|

函数y=sin(ωx+φ)(ω>0,|φ|
函数y=sin(ωx+φ)(ω>0,|φ|

函数y=sin(ωx+φ)(ω>0,|φ|
函数y=sin(ωx+φ)(ω>0,|φ|0,|φ|T=2π/3==>w=2π/(2π/3)=3A=1∴f(x)=sin(3x+φ),f(π/4)=sin(3π/4+φ)=1==>3π/4+φ=π/2==>φ=π/4∴y=sin(3x+π/4)
(2)解析：y=sinx==>y=sin(3x+π/4)
将y=sinx图像左移π/4单位,得y=sin(x+π/4)图像；
将横坐标缩小到原来的1/3,纵坐标不变,得y=sin(3x+π/4)图像；
(3)解析：因为a不确定,无法完成,不同的a值可得不同实根
如当a=1/2时,在【0,2π】内
f（x）=1/2的所有实数根为：
3x+π/4=2kπ+π/6==>x=2kπ/3-π/36
当k=1,2,3时,x=23π/36,47π/36,71π/36
3x+π/4=2kπ+5π/6==>x=2kπ/3-7π/36
当k=1,2,3时,x=17π/36,41π/36,65π/36