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1 of 2 killer questions-Trig

  • Thread starter TonyC
  • Start date
86
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1 of 2 killer questions--Trig

suppose the depth of the tide in a certain harbor can be modeled by y=21-5cos(pi t)/6, where y is the water detph in feet and t is the time in hours. Consider a day in which t=0 represents 12:00 midnight. For that day, when are the first high tide and the first low tide and what is the water depth at each time?

I came up with:
High tide: 7 am, 16 feet; low tide 13 noon, 15 feet.

That is wrong.....can anyone help? :confused:
 

Answers and Replies

VietDao29
Homework Helper
1,417
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[tex] \cos 0 = 1[/tex]
[tex] \cos \pi = -1[/tex]
------
EDIT:
Do not double post.
Viet Dao,
 
99
1
It's really qouit simpel you acctuaelly want to know when cos(pi*t/6) equals 1 and -1 (max and min). After you have done this you only have to find y for the calculated values of t. The answeres I got this way where: high tide at 6AM and 6PM with 26 feet and low tide at midnigth and noon with 16 feet.
 
86
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The light is shining....thank you
:bugeye:
 

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