Determine the amplitude and period of y 3cos pi4 x and sket

Determine the amplitude and period of y = 3cos(- pi/4 x) and sketch the graph of this function (one period only). Use the grid provided in Figure 2 below. Make sure to indicate key points on your graph.

Solution

y= 3cos(-pi x/4)

This is of the form y=Acos(Bx+C)

Where A is the amplitude which is 3 here

Period=2pi/B =2pi/pi/4=8