What happens to the function f (x) = acosx when the value of a increases?

The period decreases.

The period increases.

The amplitude decreases.

The amplitude increases.

The amplitude increases.

The maximum value of y = cos (x) is 1; the minimum is - 1. Hence the amplitude of original cosine being 1.

Since a is the coefficient outside, it will vertically expand cosine, making amplitude larger. The amplitude will actually be equal to the value of a.