At midnight, at high tide, the depth of water on a beach is 7 feet. Six and one-half hours later, the depth of the water at low tide is 3 feet. Assume that the depth of the water varies sinusoidally with time. Let t represent the number of hours since midnight. a. The amplitude is ?
b. The period is ?
C. The phase shift is ?
d. The midline is y ?

What is the depth of the water att = 4 hours?