Question 1214

Vectors I: Basics, Dot and Cross Products
2014 Paper 1 Question 3 Variant

Question

(i)
Find a unit vector n{\mathbf{n}} such that
n×(4i+3j)=0.\mathbf{n} \times (4 \mathbf{i} + 3 \mathbf{j}) = \mathbf{0}.
[2]
(ii)
Find the cosine of the acute angle between 4i+3j{4 \mathbf{i} + 3 \mathbf{j}} and the z-{z\textrm{-}}axis.
[1]

Answer