30. The horizontal displacement of a swinging pendulum is given by f(t) = 1.5 cos(t) , where f(t) is the horizontal displacement, in centimetres, from the lowest point of the swing, as a function of time, t, in seconds. (Set calculator to RAD) a) Determine the horizontal displacement at 6 seconds. (2 marks) b) Determine the instantaneous rate of change at 4 seconds. Show all steps for full marks