If a line has direction ratios $2, -1, -2$, determine its direction cosines.
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → $(\frac{2}{3}, -\frac{1}{3}, -\frac{2}{3})$ ##
Direction cosines are
$\frac{2}{\sqrt{2^2 + (-1)^2 + (-2)^2}}, \frac{-1}{\sqrt{2^2 + (-1)^2 + (-2)^2}}, \frac{-2}{\sqrt{2^2 + (-1)^2 + (-2)^2}}$
Or $\frac{2}{3}, -\frac{1}{3}, -\frac{2}{3}$.