29. The largest tidal difference in the world is in the Bay of Fundy off the Atlantic coast of Canada. At Hopewell, the depth of the water at low tide is about 2.0 meters and at high tide about 12.0 meters. The tidal cycle is about 12 hours. Assuming high tide at 6:45 am one day, use the cosine function to express a function D(1) representing the depth of the water (unit: meters) with respect to the time since midnight