Important Questions for CBSE Class 12 Maths Chapter 10 - Vector Algebra


CBSE Class 12 Maths Chapter-10 Important Questions – Free PDF Download

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CBSE Class 12 Mathematics Important Questions Chapter 10 – Vector Algebra


1 Mark Questions

1. Is the measure of 5 seconds is scalar or vector?
Ans: Scalar


2. Find the sum of the vectors.

Ans: 


3. Find the direction ratios and the direction cosines of the vector 
Ans: D.R of 

D.C of 


4. Find the angle between vectors 
Ans: 


5. Vectors be such that then is a unit vector. Find angle between.
Ans: 



6. Is the measure of 10 Newton is scalar or vector.
Ans:Vector


7. Write two different vectors having same magnitude.
Ans: 



8. Find the direction ratios and the direction cosines of the vector 
Ans: D.R of 


9. Find 
Ans:




10. If 
Ans: 





11. Is the measure of 20 m/s towards north is scalar or vector.
Ans: Vector
12. 
Ans: 


13. Find the direction ratios and the direction cosines of the vector 
Ans: D.R of 

D.C of 


14. Evaluate the product 
Ans:


15. Find if 
Ans: 


16. Is the measure of 30 m/s towards north is scalar or vector.
Ans: Scalar


17. Compute the magnitude of
Ans: 


18. Find the direction ratios and the direction cosines of the vector 
Ans: D.R of 

D.C of 


19. Is unit vector and Then find 
Ans:



20. Show that 
Ans: 




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4 Mark Questions

1. Find the unit vector in the direction of the sum of the vectors 
Ans: Let 



The required unit vector is



2. Show that the points are the vertices of right angled triangle.
Ans: 




Hence, the is a right angled triangle.


3. Show that the points are collinear.
Ans: 





Hence points A, B, C are collinear.


4. If are unit vector such that find the value of 
Ans: 








5. If are such that is then find the value of.
Ans: 






6. Consider two point P and Q with position vectors. Find the positions vector of a point R which divides the line joining P and Q in the ratio 2:1 (i) internally (ii) externally.
Ans: (i) 

(ii) 


7. Show that the points A, B, C with position vectors respectively are collinear.
Ans: 






Thus but one point B is common to both vectors hence A, B, C are collinear.


8. Find a unit vector to each of the vectors 
Ans: A vector which is to both is giving by





Req. unit vector is


9. The scalar product of the vector with a unit vector along the sum of vectors is equal the one. Find the value of 
Ans: 


Unit vector along









10. Find the area of the with vertices A (1, 1, 2) B (2, 3, 4) and C (1, 5, 5).
Ans: A (1, 1, 2) B(2, 3, 4) C (1, 5, 5)

OB¯¯¯¯¯¯¯¯=2i^+3j^+4k^OB¯=2i^+3j^+4k^
OC¯¯¯¯¯¯¯¯=i^+5j^+5k^OC¯=i^+5j^+5k^






11. Show that the points A (1, -2, -8) B (5, 0, -2) and C (11, 3, 7) are collinear, and find the ratio in which B divides AC.
Ans:A (1, -2, -8), B (5, 0, -2), C (11, 3, 7)








Thus and one point B is common there fore A, B, C are collinear and B divides AC in 2:3.


12. Find a vector which is to both and and .=15
Let 



Ans:







On solving equation (i) and (ii)



Put x, y, z in equation (iii)






13. Let be three vectors such that and each one of them being to the sum of the other two, find 
Ans: 




14. If 

Find the angel between the vectors 
Ans: 








15. Find the sine of the angel between the vectors.


Ans: 




16. Three vectors satisfy the condition Evaluate the quantity if 
Ans: 




Adding (i) (ii) and (iii)


17. If with reference to the right handed system of mutually unit vectors then express in the form, where is || to and isto 
Ans: 






18. If be three vectors such that and find the angle between 
Ans: 






19. Find the area of the ||gm whose adjacent sides are represented by the vectors, 
Ans: 



20. Find the vector joining the points P (2, 3, 0) and Q (-1, -2, -4) directed from P to Q. Also find direction ratio and direction cosine.
Ans: