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Question
Direction cosines of the line passing through the points A (- 4, 2, 3) and B (1, 3, -2) are.........
Options
`+-1/sqrt51,+-5/sqrt51,+-1/sqrt51`
`+-5/sqrt51, +-1/sqrt51, +- (-5)/sqrt51`
`+-sqrt5,+-1,+-5`
`+-sqrt51,+-sqrt51+-sqrt51`
Solution
The direction ratios of the line are 1 + 4, 3 − 2, −2 − 3 i.e., 5, 1, −5
∴ the direction cosines of the line are
`+-5/sqrt(5^2+1^2+(-5)^2), +-1/sqrt(5^2+1^2+(-5)^2), +- -5/sqrt(5^2+1^2+(-5)^2)`
i.e `+-5/sqrt51, +-1/sqrt51, +- -5/sqrt51`
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