At 12 noon the position vectors r and the velocity vectors v of two ships A and B are
rA = (2i+j)km vA = (3i+j)kmh^-1
rB = (-i-4j)km vB = (11i+3j)kmh^-1
(a) Show that at time t h after noon the position vector of B relative to A is given by:
(b) Show that the distance d km between the vessels, at this time, is given by
d^2=68[t^2 - t+1/2]
(c) Hence show that the ships are nearest together at 12.30 p.m and find the distance between them at this time.