The position r of a particle moving in an xy plane is given by r=(4.00t31.00t)i^+(5.001.00t4)j^ with r in meters and t in seconds. In unit-vector notation, calculate (a)r, (b)v, and (c)a for t = 3.00 s. (d) What is the angle between the positive direction of the x axis and a line tangent to the particle's path at t = 3.00 s? Give your answer in the range of (-180^o; 180^o).