Write the sine functions based on the sine form transformation

Given y = sin(x), which is curve1. Write the following analytical expressions after each action. Action1: move all points in curve1 right pi/4 units, get curve2. Write the analytical expression
for curve2. Action2: double all x-coordinates in curve2 and keep the y-coordinate not change, get curve3. Write the analytical expression for curve3. Action3: double all y-coordinate in curve3
and keep x-coordinate not change, get curve4. Write the analytical expression for curve4.