73. Normal acceleration of a point moving along a circle with a radius r = 4 m, is given by the equation an = A + Bt + Ct2 (A = 1 m / s2, B = 6 m / s3, C = 9 m / c4). Determine: 1) the tangential acceleration of a point; 2) the path traversed by the point in time t1 = 5 s after the start of the movement; 3) total acceleration at time t2 = 1