Question

Which of the following cosine functions has a period of 3 π ?

Answer 1

Answer:

c. y= cos2/3x

Step-by-step explanation:

Answer 2

ANSWER

C.

$y = \: \cos( \frac{2}{3}x )$

EXPLANATION

The period of a cosine function is calculated using the formula;

$T= \frac{2 \pi}{b}$

Therefore , if the period is 3π, then

$\frac{2 \pi}{b} = 3\pi$

We solve b to obtain,

$b = \frac{2}{3}$

This implies that, the given cosine function must have an equation of the form

$y = a \: \cos( \frac{2}{3}x )$

Among the options, the function in this form is:

$y = \: \cos( \frac{2}{3}x )$

The correct choice is C.