At High Tide, the Water Level Is 6 Feet Below

Short Answer

At high tide, the water level is 6 feet below a certain pier. At low tide, the water level is 18 feet below the pier. Assuming sinusoidal behavior, let = the water level relative to the pier, at time t (in hours). At t = 0 the water is -12 feet and falling until it reaches the first low tide at t = 3. Give a formula for .