Given the graph above, write the equation as a cosine function
a. y = .25 cos ø
b. y = .75 cos 2ø
c. y = -.75 cos 2ø
d. y = -.50 cos 3ø
e. y = cos 4ø

Option B

Step-by-step explanation:

The general cosine function has the following form  

Where A is the amplitude: half the vertical distance between the highest peak and the lowest peak of the wave.  

is the period: time it takes the wave to complete a cycle.

k is the vertical displacement.

The maximum value of y is is 0.75 and the minimum is -0.75. Then the amplitude A is:  

Then

The cycle is repeated every units  

So the period is

Thus:

The function is:

when y is maximum therefore As shown in the graph