Let A, B, C be the points with position vectors 10i + 3j, 12i − 5j, ai + 11j. Then,
Vector AB = Position vector of B − Position vector of A
= 12i − 5j − 10i − 3j
= 2i − 8j
Vector BC = BC→ = Position vector of C −Position vector of B
= ai + 11j − 12i + 5j
= (a−12)i + 16j
Since, A, BA, B and CC are collinear.
