- #1
flyinghigh
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I'm having a bit of trouble working out the cosine function for the data I have on tide charts.
I need to put the data provided into the cosine function y=acos(nx-b)+c
Morning average high tide: 5.137 metres
Morning average low tide: 1.29 metres
Afternoon average high tide: 4.732 metres
Afternoon average low tide: 1.35
Average high tide: 4.93 metres
Average low tide: 1.32 metres
Average time between high tide: 12.18 hours
Average time between low tides: 12.15 hours
y=acos(nx-b)+c or y=Acos(Bx + C) + D
Through research I know that amplitude, a, will be (average high tide - average low tide) / 2
so amplitude = 1.805
Period,n or B, will be average time between high tides, so 12.29
Now, I know that these are correct, but I'm no quite sure why. Nor do I know what the phase shift, b or C, will be. I have a feeling that c or D will be (average high tide + average low tide) / 2 = 3.125, but once again don't know why..
Any help would be most appreciated!
flyinghigh
Homework Statement
I need to put the data provided into the cosine function y=acos(nx-b)+c
Morning average high tide: 5.137 metres
Morning average low tide: 1.29 metres
Afternoon average high tide: 4.732 metres
Afternoon average low tide: 1.35
Average high tide: 4.93 metres
Average low tide: 1.32 metres
Average time between high tide: 12.18 hours
Average time between low tides: 12.15 hours
Homework Equations
y=acos(nx-b)+c or y=Acos(Bx + C) + D
The Attempt at a Solution
Through research I know that amplitude, a, will be (average high tide - average low tide) / 2
so amplitude = 1.805
Period,n or B, will be average time between high tides, so 12.29
Now, I know that these are correct, but I'm no quite sure why. Nor do I know what the phase shift, b or C, will be. I have a feeling that c or D will be (average high tide + average low tide) / 2 = 3.125, but once again don't know why..
Any help would be most appreciated!
flyinghigh