WAEC - Further Mathematics (2013 - No. 34)

P and Q are the points (3, 1) and (7, 4) respectively. Find the unit vector along PQ.
\(\begin{pmatrix} 4 \\ 3 \end{pmatrix}\)
\(\begin{pmatrix} 0.6 \\ 0.8 \end{pmatrix}\)
\(\begin{pmatrix} 0.8 \\ 0.6 \end{pmatrix}\)
\(\begin{pmatrix} -0.8 \\ 0.6 \end{pmatrix}\)

Explanation

\(PQ = \begin{pmatrix} 7 - 3 \\ 4 - 1 \end{pmatrix}\)

\(= \begin{pmatrix} 4 \\ 3 \end{pmatrix}\)

\(\hat{n} = \frac{\overrightarrow{PQ}}{|PQ|} \)

\(|PQ| = \sqrt{4^{2} + 3^{2}} = \sqrt{25} = 5\)

\(\hat{n} = \frac{1}{5}\begin{pmatrix} 4 \\ 3 \end{pmatrix} = \begin{pmatrix} 0.8 \\ 0.6 \end{pmatrix}\) 

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