A particle's trajectory is described by x = (1/2*t^3 - 2*t^2) m and y = (1/2*t^2 - 2*t) m, where t is in s. What is the particle's direction of motion, measured as an angle from the x-axis, at t = 0 s? What is the particle's direction of motion, measured as an angle from the x-axis, at t = 3 s?