Direction Cosines and Direction Ratios — Maths STD 12 Science — Question
Gujarat BoardEnglish MediumSTD 12 ScienceMathsDirection Cosines and Direction Ratios2 Marks
Question
If a line has direction ratios 2, -1, -2, determine its direction cosines.
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Answer
Let the direction cosines of a line be l, m and n. Now,$\text{l}=\frac{2}{\sqrt{2^2+(-1)^2+(-2)^2}}=\frac{2}{3}$
$\text{m}=\frac{-1}{\sqrt{2^2+(-1)^2+(-2)^2}}=\frac{-1}{3}$ $\text{n}=\frac{-2}{\sqrt{2^2+(-1)^2+(-2)^2}}=\frac{-2}{3}$ $\therefore$ The direction consines of the line are $\frac{2}{3},\frac{-1}{3},\frac{-2}{3}.$
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