75. Ebb and Flow On a particular Labor Day, the high tide in Southern California occurs at 7:12 A.M. At that time you measure the water at the end of the Santa Monica Pier to be 11 ft deep. At 1:24 p.M. it is low tide, and you measure the water to be only 7 ft deep. Assume the depth of the water is a sinusoidal function of time with a period of 1/2 a lunar day, which is about 12 hr 24 min .
(a) At what time on that Labor Day does the first low tide occur?
(b) What was the approximate depth of the water at 4:00 A.M. and at 9:00 P.M.?
(c) What is the first time on that Labor Day that the water is 9 ft deep?