Modeling Tidal Changes with Cosine Functions

[jlhmom]

Homework Statement

High tide at 4am with a depth of 6 meters. Low tide at 10 am with a depth of 2 meters. Model the problem using the equation to show the depth of the water t hours after midnight.

Homework Equations

y= A cos(Bx+C) +D

The Attempt at a Solution

: I am not getting the values that I should I think.

I have A=2, D=4, B=pi/6, C=pi/6. They don't seem right though.

 

[Dick]

Homework Statement

High tide at 4am with a depth of 6 meters. Low tide at 10 am with a depth of 2 meters. Model the problem using the equation to show the depth of the water t hours after midnight.

Homework Equations

y= A cos(Bx+C) +D

The Attempt at a Solution

: I am not getting the values that I should I think.

I have A=2, D=4, B=pi/6, C=pi/6. They don't seem right though.

No, it's not right. Your C value is wrong. You need to have Bx+C equal to 0 when x=4 and equal to pi when x=10.

 

[jlhmom]

Ok. thanks Dick. I got -2pi/3 for a better answer for C.