Application (10 marks) 20. Find b and c such that [-2.b.7] and [c,6,21] are collinear. 121 21. A plane is steering at $83E at an air speed of $50 km/h. The wind is from N70 E at 85 km/h. Find the ground velocity of the plane to 1 decimal. 141 22. Given the points of a triangle; A(-1,3.5) B(2,1.3) and C(-1.1.4). Determine the area of the triangle. 14]