How do you graph #y = -3sin (1/2x - pi/4) #?
With reflection about the x-axis.
The (-) before the A indicates a reflection about the x-axis
A is amplitude in absolute value |A|
To find the period for sin you use
To find the phase shift you use
Divide the period by 4 to get the 4 sections of the graph.
Start your first point on the graph using the phase shift, which is
You may find it easiest to make each tick mark on the x-axis=