1. What is the period of the function?

y=4 cos pi x

A. 1
B. 2
C. pi
D. 2pi

To determine the period of the function y = 4cos(πx), we need to understand the concept of the period of a trigonometric function.

The period of a trigonometric function is the length of the interval over which the function repeats itself. Specifically for cosine functions, the period is given by the formula:

Period = 2π / |coefficient of x|

In this case, the coefficient of x is π. Therefore, we can calculate the period as follows:

Period = 2π / π = 2

So, the period of the given function is 2.

Therefore, the correct answer is B. 2.