Re: Sine or Cosine Wave Equation?

Would someone check if I have the correct equation to
this problem?

A high tide of 6 feet occurs at 4:00 am and a low
tide of 2.5 feet at 10:00am.Find the equation.

I got the equation Y=sin(pi/3X +4)+4.25.
I wonder if the equation is suppose to be a sine wave
or a cosine wave. Help Please!

Well, you can write it as a sine or cosine, but with phase offsets that differ by 90 degs.

Assume the height of the tide is given by

H = A*cos(N*t + P) + B

Where t is in hours.

There are two high tides in a day, so N would be

N = 2pi/(12 hr) = pi/6 * (rad/hr)

At high tide cos(N*t + P) must be +1. From that can you find P?

Now what about A and B? At high tide cos(N*t + P) will be +1, and at low tide -1. Knowing that, how do you find A and B?

- MO
.

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