A harbourmaster models three navigation buoys A, B and C using position vectors relative to a fixed origin O (the harbour), with distances in metres: OA = 4i + 2j, OB = 16i + 8j, OC = 22i - 4j.
(a)Show that O, A and B are collinear, and find the ratio OA : AB.(3)
(b)Find the vectors BC and AC, and show that |AB|^2 = |BC|^2 = 180 and |AC|^2 = 360.(5)
(c)Hence show that triangle ABC is a right-angled isosceles triangle, stating clearly where the right angle is located.(3)
(d)Find the exact perimeter of triangle ABC, in metres.(2)
(Total for Question 12 is 13 marks)