27. As Ricky rides his rocking horse, the distance from the horse's tail to the ground, in centimetres, in terms of seconds, is modelled by the equation @(6) = 2 sin(7205)" + 20. How long does it take for the tail to go all the way up and all the way down once? a. 20 s c. 2 s b. 4s d. 0.5 s