Answer:
A
Step-by-step explanation:
To find the amplitude of the function f(x) = cos(3x + π), we look at the coefficient of the cosine function. The general form of a cosine function is f(x) = A * cos(Bx + C), where A represents the amplitude.
In this case, the coefficient of x is 3, so the amplitude is the reciprocal of that coefficient. Therefore, the amplitude of the function is 1/3.
So the correct answer is A. 1/3.
