SOLUTION: For the following table of data, determine an equation of a cosine function that satisfies the given data. The link to the table is here: https://gyazo.com/330133762196a7fabc67d

x (degrees) -60 -30  0  30  60  90 120

y            10   8  6   8  10   8   6


The function completes a cycle between (-60,10) and (60,10); 10 is the maximum value; 6 is the minimum value; 8 is the centerline value.  That immediately tells us d=8 and a=2.


It also tells us that the period is 120 degrees; that means parameter b is 360/120 = 3.


Finally, the basic cosine function has its maximum value at x=0.  The given function has a maximum values at x=60; so c is 60.


Now we have all the parameters we need to write the equation:

a = 2

b = 3

c = 60

d = 8





Here is a graph, showing constant functions at the minimum and maximum values and the center line....