document.write( "Question 1113618: suppose that the water level varies 70 inches between low tide at 8:.40 AM and high tide at 2:55PM .what he cosine function that models the variation in inches above and below the average water level as a function of the number of hours since 8:40AM .at what point in the cycle does the function cross the midline.what does the midline represent. \n" ); document.write( "
Algebra.Com's Answer #728699 by Alan3354(69443)\"\" \"About 
You can put this solution on YOUR website!
suppose that the water level varies 70 inches between low tide at 8:40 AM and high tide at 2:55 PM. what he cosine function that models the variation in inches above and below the average water level as a function of the number of hours since 8:40AM.
\n" ); document.write( "----
\n" ); document.write( "1455 - 0840 = 7:15 hours for a half-cycle (notice the arithmetic is easy by not using AM & PM for times)
\n" ); document.write( "The period is 2x that = 14:30 = 14.5 hours
\n" ); document.write( "---
\n" ); document.write( "The amplitude = 70/2 = 35 inches, ie, 35 above the mean and 35 below.
\n" ); document.write( "h(t) = 35*cos(2pi*t/14.5) --> cosine function with max at t = 0
\n" ); document.write( "h(t) = 35*cos(4pi*t/29 + 180) --> function of the tides, t in hours
\n" ); document.write( "====================
\n" ); document.write( "at what point in the cycle does the function cross the midline.
\n" ); document.write( "At t = 0840 + 7.25 hours + 14.5*n hours where n = integer
\n" ); document.write( "-----------
\n" ); document.write( "what does the midline represent.
\n" ); document.write( "It's the x axis and MSL, Mean Sea Level \n" ); document.write( "
\n" );