Question

Write the direction cosines of the vectors $-2\hat{i}+\hat{j}-5\hat{k}$.

Answer 1

Given: $-2\hat{i}+\hat{j}-5\hat{k}$
Then, its direction cosines are:
$\frac{-2}{\sqrt{{\left(-2\right)}^2+1^2+{\left(-5\right)}^2}},\frac{1}{\sqrt{{\left(-2\right)}^2+1^2+{\left(-5\right)}^2}},\frac{-5}{\sqrt{{\left(-2\right)}^2+1^2+{\left(-5\right)}^2}}$ or, $\frac{-2}{\sqrt{30}},\frac{1}{\sqrt{30}},\frac{-5}{\sqrt{30}}$