Question 1214

Vectors I: Basics, Dot and Cross Products

2014 Paper 1 Question 3 Variant

Question

(i)

Find a unit vector

{\mathbf{n}}

such that

\mathbf{n} \times (- 8 \mathbf{i} + 4 \mathbf{j} + \mathbf{k}) = \mathbf{0}.

[2]

(ii)

Find the cosine of the acute angle between

{- 8 \mathbf{i} + 4 \mathbf{j} + \mathbf{k}}

and the

{y\textrm{-}}

axis.

[1]