Question

Determine the amplitude (A), period (P), and phase shift (PS) of the function f(x) = 7cos (9x).

Answer 1

D) A=7,
`P=(2\pi)/(9)`, PS=(0,0) is correct.

Explanation:

Given function is
`f(x)=7\cos(9x)`

Compare that with formula
`f(x)=A\cos(Bx-C)+D`

we get:

A=7, B=9, C=0, D=0

In that formula, amplitude is given by formula |a|

Hence amplitude = |a|=|7|= 7

In that formula, period is given by formula
`(2\pi)/(B)`

Hence period =
`(2\pi)/(B)=(2\pi)/(9)`

Phase shift is given by formula
`(C)/(B)`

Hence phase shift =
`(C)/(B)=(0)/(9)=0`

So the last choice D) A=7,
`P=(2\pi)/(9)`, PS=(0,0) is correct.