要画y=sin(2x)图像y=2sinx图像和y=sina(2x+π/4)图像,请帮我列三个的描点表!

y=sin(2x)
x 0 π/4 π/2 3π/4 π
y 0 1 0 -1 0
y=2sinx
x 0 π/2 π 3π/2 2π
y 0 2 0 -2 0
y=sina(2x+π/4)
x -π/8 π/8 3π/8 5π/8 7π/8
y 0 1 0 -1 0
注：我不知道那个y=sina(2x+π/4)里的a什么意思,当作y=sin (2x+π/4)的来写