What is the equation of the cosine function described?

Question

A cosine function is a reflection of its parent function over the x-axis. The amplitude of the function is 9, the vertical shift is 11 units down, and the period of the function is 12π7. The graph of the function does not show a phase shift.

 

What is the equation of the cosine function described?

Correctly complete the equation of the function.

f(x)= _9_cos( __ x ) __ 

 

Answer choices:

9  ,  −20  ,  −11  ,  −9  ,  −2  ,  2  ,  11  ,  20  ,  7π/12  ,  12π/7  ,  7/6  ,  6/7

Answer 1

Period = 2*PI/|b|. We are given the period, we just need to solve for b, which will be the value placed before x.