# How do you write an equation of the cosine function with amplitude 3 and period 4π?

##### 2 Answers

May 28, 2018

May 28, 2018

The general form for the cosine function is:

The amplitude is:

The period is:

The phase shift is

The vertical shift is D

#### Explanation:

Given:

The amplitude is 3:

The above implies that A could be either positive or negative but we always choose the positive value because the negative value introduces a phase shift:

Given:

The period is

Nothing is said about the phase shift and the vertical shift, therefore, we shall assume that

Substitute these values into the general form: