The water level (in feet) in a harbor during a certain 24-hr period is approximated by the function
H(t) = 3.8 cos s [π(t-7/6)] - +7.9 (0 ≤ t ≤ 24)
at time t (in hours) (t = 0 corresponds to 12 midnight).
(a) Find the rate of change of the water level at 5 A.M. Round your answer to four decimal places, if necessary.
(b) Find the water level at 5 A.M. Round your answer to four decimal places, if necessary.