Question

Find the direction cosines of the following vectors:
\[3 \hat{i} - 4 \hat{k}\]

Answer 1

We have, \[3 \hat{i} - 4 \hat{k}\]  
The direction cosines are \[\frac{3}{\sqrt{3^2 + 0 + \left( - 4 \right)^2}} , \frac{0}{\sqrt{3^2 + 0 + \left( - 4 \right)^2}} , \frac{- 4}{\sqrt{3^2 + 0 + \left( - 4 \right)^2}}\]   or,
\[\frac{3}{5}, 0, \frac{- 4}{5}\]