Question

In a tidal river, the time between high and low tide is 7.6 hours. At high tide the depth of water is 17.7 feet, while at low tide the depth is 5.1 feet. Assume the water depth as a function of time can be expressed by a trigonometric function (sine or cosine).Write an equation for the depth f(t) of the tide (in feet) t hours after 12:00 noon.