the minimum depth, d (in metres) of water in a harbour, t hours after midnight, can be approximated by the function: d(t) = 5cos(0.5t)+12, where t is more than or equal to 0 and less than or equal to 24. a) determine the maximum and minimum depths of water. b) determine the period of the function. c) what is the depth of water at 2am. d) a ship, which requires a minimum depth of 8.5 m is docked by midnight. by what time, to the nearest minute, must it leave to prevent being grounded.