Question

A sound wave is modeled with the equation . y=1/4cos 2pi/3treta

a. Find the period. Explain your method.
b. Find the amplitude. Explain your method.
c. What is the equation of the midline? What does it represent?

A- The period can not be found because there is no time in the equation.

B- Amplitude will be 1/4. I don't know exactly how to explain it...

C- I don't know about c , I need help

Answer 1

You should find the standard form of a cosine curve in your text or in your notes.

for y = a cos (kØ) ,
the amplitude is |a| and
the period is 2π/k in radians or 360°/k in degrees

so you have y = (1/4)cos (2π/3 Ø)

your amplitude is correct
period = 2π/(2π/3)
= 2π(3/(2π)) = 3 radians

I will assume that by the "midline" you mean the Ø axis.

You should really study and memorize the basic cosine curve.

Answer 2

yeah but I can't type "Ø" unless i copy and paste it , Thanks though