Question

The water depth in a harbor is 12m at high tide and 4m at low tide. One cycle is completed every 12 hours.
a) Sketch the graph comparing the depth of the water and time for a 24-hour period, starting a low tide.
b) Determine an equation of a cosine function that represents the water depth, in meters, as a function of the time.

Answer 1

Cannot sketch on these posts.

Answer 2

amplitude = (12-4)/2 = 4
center line is at y=(12+4)/2 = 8
period = 12, so k = π/6
minimum is at t=0, so
y = 8 - 4cos(π/6 t)