y=3sin(2x+π/3)
2x+π/3=0,即：x=-π/6时,y=0
2x+π/3=π/6,即：x=-π/12时,y=3/2
2x+π/3=π/4,即：x=-π/24时,y=(3√2)/2
2x+π/3=π/3,即：x=0时,y=(3√3)/2
2x+π/3=π/2,即：x=π/12时,y=3
2x+π/3=2π/3,即：x=π/6时,y=(3√3)/2
2x+π/3=3π/4,即：x=5π/24时,y=(3√2)/2
2x+π/3=5π/6,即：x=π/2时,y=3/2
2x+π/3=π,即：x=π/3时,y=0
……
将上述各点描述在直角坐标中,将各点连接,得到函数的图像.
其实,未必一定要五点法.
对于作图来说,五点有些少,