Answer:
Period =

Amplitude = 4
Explanation:
To find the answer, use the form acos(bx - c) + d:
a = -4
b = 8
c = 0
d = 0
The amplitude is the absolute value of a, so:
|a| = |-4| = 4
To find the period, use this equation:

Replace b with 8 in the formula and solve:
Simplify
So, the period is equal to

Hope this helps!!