Example, 2 - Chapter 11 Class 12 Three Dimensional Geometry

Last updated at August 8, 2026 by

Example 2 - If a line has direction ratios 2, -1, 2, direction cosines - Examples

part 2 - Example, 2 - Examples - Serial order wise - Chapter 11 Class 12 Three Dimensional Geometry

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Example 2 If a line has direction ratios 2, ā€“ 1, ā€“ 2, determine its direction cosines.If direction ratios of a line are a, b, c direction cosines are š’‚/āˆš(š’‚^šŸ + š’ƒ^šŸ + š’„^šŸ ) , š’ƒ/āˆš(š’‚^šŸ + š’ƒ^šŸ + š’„^šŸ ) , š’„/āˆš(š’‚^šŸ + š’ƒ^šŸ + š’„^šŸ ) Given, Direction ratios = 2, āˆ’1, āˆ’2 āˆ“ š‘Ž = 2, b = āˆ’1, c = āˆ’2 Also, āˆš(š’‚^šŸ + š’ƒ^šŸ + š’„^šŸ ) = āˆš(22 + (āˆ’1)2 + (āˆ’2)2) = āˆš(4 + 1 + 4) = āˆš9 = 3 Direction cosines = š‘Ž/āˆš(š‘Ž^2 + š‘^2 + š‘^2 ) , š‘/āˆš(š‘Ž^2 + š‘^2 + š‘^2 ) , š‘/āˆš(š‘Ž^2 + š‘^2 + š‘^2 ) = šŸ/šŸ‘ , (āˆ’šŸ)/šŸ‘ , (āˆ’šŸ)/šŸ‘

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