[填空题]
In this question, distancesve0 lwuoaul;j9fuztd /+ 8p +. are mnx2.u:b 0t57fraf1f2(x p fx4c t w g.6iwtdyneasured in kilometres.
Two tankers, A and B , are observed from an origin O . Relative to O , their position vectors at time t hours after 6:00pm are given by