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Tamil Nadu Board of Secondary EducationHSC Science Class 11

Find the direction cosines and direction ratios for the following vector ijk3i^+j^+k^

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Question

Find the direction cosines and direction ratios for the following vector

`3hat"i" + hat"j" + hat"k"`

Sum
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Solution

The direction ratios of the vector `3hat"i" + hat"j" + hat"k"` are (3, 1, 1)

The direction cosines of the vector `3hat"i" + hat"j" + hat"k"` are

`3/sqrt(3^2 + 1^2 + 1^2), 1/sqrt(3^2 + 1^2 + 1^2), 1/sqrt(3^2 + 1^2 + 1^2)`

`3/sqrt(9 + 1 + ), 1/sqrt(9 + 1 + 1), 1/sqrt(9 + 1 + 1)`

`(3/sqrt(11), 1/sqrt(11), 1/sqrt11)`

Direction ratios = (3, 1, 1)

Direction cosines = `(3/sqrt(11), 1/sqrt(11), 1/sqrt11)`

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Chapter 8: Vector Algebra - Exercise 8.2 [Page 68]

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Samacheer Kalvi Mathematics - Volume 1 and 2 [English] Class 11 TN Board
Chapter 8 Vector Algebra
Exercise 8.2 | Q 3. (ii) | Page 68

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