Working with vectorsUsing and finding unit vectors

Evaluate scalar product and determine the angle between two vectors

Part ofMathsGeometric skills

Using and finding unit vectors

The basic unit vectors are \(i = \left( \begin{array}{l}1\\ 0\\0\end{array} \right)\), \(j=\left(\begin{array}{l}0\\1\\0\end{array}\right)\) and \(k = \left(\begin{array}{l} 0\\ 0\\1\end{array} \right)\)

Any vector can be written in terms of \(i\), \(j\) and \(k\). For example:

\(\left(\begin{array}{l}\,\,\,\,\,\,3\\\,\,\,\,\,4\\- 2\end{array} \right) = \left(\begin{array}{l}\,3\\0\\0\end{array} \right) + \left(\begin{array}{l}\,0\\4\\0\end{array} \right) + \left(\begin{array}{l}\,\,\,\,\,0\\\,\,\,\,\,0\\- 2\end{array} \right)\)

\(= 3\left(\begin{array}{l}1\\0\\0\end{array} \right) + 4\left( \begin{array}{l}0\\1\\0\end{array} \right) - 2\left( \begin{array}{l}0\\0\\1\end{array} \right)\)

\(= 3i + 4j - 2k\)

Question

Express \(\left( \begin{array}{l} \,\,\,\,\,5\\\,\,\,\,\,0\\ - 1\end{array} \right)\) in terms of unit vectors.

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