Question 1207

Vectors I: Basics, Dot and Cross Products
2007 Paper 1 Question 6 Variant

Question

Referred to the origin O,{O,} the position vectors of the points A{A} and B{B} are
3i+3j2k and 5i+3j+pk\begin{align*} && 3 \mathbf{i} + 3 \mathbf{j} - 2 \mathbf{k} \\ \textrm{ and } \quad && - 5 \mathbf{i} + 3 \mathbf{j} + p \mathbf{k} \end{align*}
respectively.
(i)
Find the value of p.{p.}
[2]
(ii)
Find the position vector of the point M{M} on the line segment AB{AB} such that AM:MB=2:1.{AM:MB = 2:1.}
[3]
(iii)
The point C{C} has position vector 3i+4j2k.{3 \mathbf{i} + 4 \mathbf{j} - 2 \mathbf{k}.} Use a vector product to find the exact area of triangle OAC.{OAC.}
[4]

Answer