How do you graph y=cos4xy=cos4x?

1 Answer
Sep 30, 2016

The period of the cosine wave y = cos kx = 2/kpi2kπ.

Here, for y = cos 4x, the period is (2pi)/4=pi/22π4=π2

Let us make a Table, with spacing pi/16π16.

for one period x in [0, pi/2]x[0,π2]

(x, y): (0, 1) (pi/16, 1/sqrt 2) (pi/8, 0), (3/16pi, -1/sqrt 2) (pi/4, -1)(x,y):(0,1)(π16,12)(π8,0),(316π,12)(π4,1)

(5/16pi,. -1/sqrt 2) (3/8pi, 0) (7/16pi, 1/sqrt 2) (pi/2, 1)(516π,.12)(38π,0)(716π,12)(π2,1)

The graph for this Table will show one full wave.

Foe successive periods, move this graph laterally ( in the x-

direction), through pi/2 =1.57π2=1.57 units..