Question

What is the period of the function f(x) = -4 cos(5x-9) - 7?
Give an exact value.
units

Answer 1

2pi/5

Explanation:

The only thing in this equation that affect the period is the '5' in front of the 'x'

cos period is usually 2pi

this is compressed by 5

period = 2pi/ 5

Answer 2

General equation

• y=Acos(Bx+C)+D

Our Equation

• y=-4cos(5x-9)-7

On comparing

• A=-4
• B=5
• C=-9
• D=-7

Now

Period

• 2π/B
• 2π/5