Edexcel P4 2021 October — Question 7

Exam BoardEdexcel
ModuleP4 (Pure Mathematics 4)
Year2021
SessionOctober
TopicVectors: Cross Product & Distances

7. With respect to a fixed origin \(O\),
  • the line \(l\) has equation \(\mathbf { r } = \left( \begin{array} { r } 4
    2
    - 3 \end{array} \right) + \lambda \left( \begin{array} { r } - 4
    - 3
    5 \end{array} \right)\) where \(\lambda\) is a scalar constant
  • the point \(A\) has position vector \(9 \mathbf { i } - 3 \mathbf { j } + 2 \mathbf { k }\)
Given that \(X\) is the point on \(l\) nearest to \(A\),
  1. find
    1. the coordinates of \(X\)
    2. the shortest distance from \(A\) to \(l\). Give your answer in the form \(\sqrt { d }\), where \(d\) is an integer. The point \(B\) is the image of \(A\) after reflection in \(l\).
  2. Find the position vector of \(B\). Solutions relying on calculator technology are not acceptable. \begin{figure}[h]
    \includegraphics[alt={},max width=\textwidth]{08756c4b-6619-42da-ac8a-2bf065c01de8-26_668_661_408_644} \captionsetup{labelformat=empty} \caption{Figure 3}
    \end{figure}