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CBSE Class 12 Math 2011 Solved Paper

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Question : 9 of 29
Marks: +1, -0
Write the direction cosines of the vector −2i^+j^−5k^-2\hat{i}+\hat{j}-5\hat{k}
Solution:  
The direction cosines of the given vector −2i^+j^−5k^-2\hat{i}+\hat{j}-5\hat{k} is given by
(−2(−2)2+(1)2+(−5)2,1(−2)2+(1)2+(−5)2,−5(−2)2+(1)2+(−5)2)\left( \frac{-2}{\sqrt{(-2)^2+(1)^2+(-5)^2}}, \frac{1}{\sqrt{(-2)^2+(1)^2+(-5)^2}}, \frac{-5}{\sqrt{(-2)^2+(1)^2+(-5)^2}} \right)
= (−230,130,−530)\left( \frac{-2}{\sqrt{30}}, \frac{1}{\sqrt{30}}, \frac{-5}{\sqrt{30}} \right)
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