Consider the triangle ABC. Let P divide the segment AB in the ratio s : t, and Q divide the segment BC in the ratio t : s.
(a) Draw a sketch of the situation.
(b) Express the vector PQ in terms of t, s, and AC.
(c) Hence explain why PQ and AC are parallel
I understand Part A and realise that the length of AB = PQ, and can also see how PQ is parallel to that of AC. Just unsure on how to express PQ.