Question 1209

Vectors I: Basics, Dot and Cross Products
2009 Paper 2 Question 2 Variant

Question

Relative to the origin O,{O,} two points A{A} and B{B} have position vectors given by a=7i+32j+22k{\mathbf{a}=7 \mathbf{i} + 32 \mathbf{j} + 22 \mathbf{k}} and b=19i10k{\mathbf{b}=19 \mathbf{i} - 10 \mathbf{k} } respectively.
(i)
The point P{P} divides the line AB{AB} in the ratio 3:1.{3:1.} Find the coordinates of P.{P.}
[2]
(ii)
Explain why AB{AB} and OP{OP} are perpendicular.
[2]
(iii)
The vector c{\mathbf{c}} is a unit vector in the direction of OP.{\overrightarrow{OP}.} Write c{\mathbf{c}} as a column vector.
[1]
(iv)
Find the area of triangle OAP.{OAP.}
[3]

Answer