1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Cosine functions and tides

  1. Dec 28, 2011 #1
    1. The problem statement, all variables and given/known data

    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.

    2. Relevant equations

    y= A cos(Bx+C) +D

    3. 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.
  2. jcsd
  3. Dec 28, 2011 #2


    User Avatar
    Science Advisor
    Homework Helper

    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.
    Last edited: Dec 28, 2011
  4. Dec 28, 2011 #3
    Ok. thanks Dick. I got -2pi/3 for a better answer for C.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook