Mathematics Part-II

Book: Mathematics Part-II

Chapter: 10. Vector Algebra

Subject: Maths - Class 12th

Q. No. 13 of Exercise 10.2

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13

Find the direction cosines of the vector joining the points A(1, 2, –3) and B(–1, –2, 1), directed from A to B.

So, and


Now we want to find the





Now, we have to find the direction cosines which are the coefficients of the unit vector in the direction of .We know that unit vector means that the magnitude of the vector is 1(unit).


It is defined as


So, we find the magnitude of first.




Therefore, The direction cosines of the given vector are .


13

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