a b c or d

Wind turbines are increasingly used to produce renewable electricity. Some of the largest ones can reach over 140 metres tall, The height of the edge of a windmill blade is modelled by the function h(t) = acos(b(t -c)) +d. A true statement about the function could be Select one: O a. the d-value can be found by averaging the maximum and minimum heights. b. the b-value is equal to 21t divided by the number of revolutions per minute. O' c. the amplitude is equal to the maximum height divided by 2. O d. the height must be at its maximum when t = 0 if c = 0