Two ships P and Q are travelling at night with constant velocities. At midnight, P is at the point with position vector (20i + 10j) km relative to a fixed origin O. At the same time, Q is at the point with position vector (14i – 6j) km. Three hours later, P is at the point with position vector (29i + 34j) km. The ship Q travels with velocity 12j km h–1. At time t hours after midnight, the position vectors of P and Q are p km and q km respectively. Find (a) the velocity of P, in terms of i and j, (b) expressions for p and q, in terms of t, i and j. At time t hours after midnight, the distance between P and Q is d km. (c) By finding an expression for PQ, show that d^2 = 25t^2 – 92t + 29^2. --- Hi... another vectors question.... i get the answers to part a and and b... however, for C i dont really know how to do this one.... maybe im lacking the principles to this question. ... If anyone could walk me through part C.. it would really help... Thanks :) PS. Do you know of any good internet source that has extensive tutorials on vectors?