Alright since my first question got deleted, I'd figured I tried to explain what I'm stuck with.

I have a sine wave that is down below.
Write an equation for the sine wave. What is the amplitude and period?
Now, you are going to determine the frequency of the tone you created.
The frequency formula is: frequency = 1/period

My exact points maybe off, mainly from my own confusion of this graph
Max Point: (-3, 2.5) (12, 2.5)
Min. Point: (4, -2.5)
Midline: y=0
Amplitude= 2.5
Period= 2π/-0.4 = -16
My equation: f(x)=2.5sin(-0.4(x-0.5))
frequency = 1/-16 (-0.0625 hertz? Or 1/-16 hertz)

I don't know if I'm completely off or on the right track, and would just like someone help me explain this a little more.
Thx!!