Karl starts the engine on his small private airplane. The engine drives a propeller with a radius of 9 feet and its centerline 12.5 feet above the ground. At idle, the propeller rotates at a constant speed of approximately 750 revolutions per minute. The height of one propeller tip as a function of time is given by h = 12.5 + 9 sin (750t), where h is the height in feet and t is the time in minutes. Find h when t = 3.5 minutes.