The NCERT Exemplar textbooks are very important for students in order to attain strong conceptual knowledge. Students can now access the NCERT Exemplar Solutions available subject-wise for getting guidance to solve the exemplar problems. All the solutions are created to help students at various levels of their difficulty. Further, all solutions are created by subject matter experts, following the latest CBSE patterns.

The 10th Chapter of NCERT Exemplar Solutions for Class 12 Mathematics is Vector Algebra. Here, students will learn introduction to vectors, its types, addition and multiplication performed on vectors, components of the vector, section formula, scalar product, projection of a vector on a line and vector product. To attain a strong grip over the concepts of this chapter, students can make use of the solutions PDF of NCERT Exemplar Solutions for Class 12 Maths Chapter 10 Vector Algebra, from the link given below.

## Download the PDF of NCERT Exemplar Solutions For Class 12 Maths Chapter 10 Vector Algebra

### Access answers to NCERT Exemplar Solutions For Class 12 Maths Chapter 10 Vector Algebra

Exercise 10.3 Page No: 215

**1. Find the unit vector in the direction of sum of vectors**

**Solution: **

Given vectors are,

**2. If find the unit vector in the direction of **

**Solution: **

**3. Find a unit vector in the direction of where P and Q have co-ordinates (5, 0, 8) and (3, 3, 2), respectively.**

**Solution: **

Given coordinates are P(5, 0, 8) and Q(3, 3, 2).

**4. If are the position vectors of A and B, respectively, find the position vector of a point C in BA produced such that BC = 1.5 BA.**

**Solution:**

**5. Using vectors, find the value of k such that the points (k, â€“ 10, 3), (1, â€“1, 3) and (3, 5, 3) are collinear.**

**Solution:**

Let the given points be A(*k*, â€“ 10, 3), B(1, â€“1, 3) and C(3, 5, 3).

**6. A vector is inclined at equal angles to the three axes. If the magnitude of is 2âˆš3 units, find.**

**Solution: **

As the vector

makes equal angles with the axes, their direction cosines should also be same

So, l = m = n

And we know that,

l^{2} + m^{2} + n^{2 }= 1 â‡’ l^{2} + l^{2} + l^{2} = 1

3l^{2} = 1

l = Â± 1/âˆš3

**7. A vector has magnitude 14 and direction ratios 2, 3, â€“ 6. Find the direction cosines and components of , given that makes an acute angle with x-axis.**

**8. Find a vector of magnitude 6, which is perpendicular to both the vectors and **

**Solution: **

**9. Find the angle between the vectors**

**Solution: **

**10. If , show that . Interpret the result geometrically?**

**Solution: **

**11. Find the sine of the angle between the vectors and **

**Solution: **

Thus, sin Î¸ = 2/âˆš7

**12. If A, B, C, D are the points with position vectors respectively, find the projection of along**

**Solution: **

We have,

**13. Using vectors, find the area of the triangle ABC with **

**vertices A(1, 2, 3), B(2, â€“ 1, 4) and C(4, 5, â€“ 1). **

**Solution: **

Given vertices A(1, 2, 3), B(2, â€“ 1, 4) and C(4, 5, â€“ 1).

**14. Using vectors, prove that the parallelogram on the same base and between the same parallels are equal in area. **

**Solution:**

Letâ€™s consider ABCD and ABFE be two parallelograms on the same base AB and between same parallel lines AB and DF.

– Hence proved.

**Long Answer (L.A.)**

**15. Prove that in any triangle ABC, , where a, b, c are the**

**magnitudes of the sides opposite to the vertices A, B, C, respectively.**

**Solution: **

In triangle ABC, the components of c are c cos A and c sin A.

**16. If determine the vertices of a triangle, show that gives the **

**vector area of the triangle. Hence deduce the condition that the three points are collinear. Also find the unit vector normal to the plane of the triangle.**

**Solution: **

**17. Show that area of the parallelogram whose diagonals are given by and is . Also find the area of the parallelogram whose diagonals are and .**

**Solution: **

Letâ€™s take ABCD to be a parallelogram such that

** **

**18. If find a vector such that **

**Solution: **

**Objective Type Questions**

**Choose the correct answer from the given four options in each of the Exercises from 19 to 33 (M.C.Q)**

**19. The vector in the direction of the vector that has magnitude 9 is**

**Solution: **

The correct option is (C).

**20. The position vector of the point which divides the join of points in the ratio 3 : 1 is**

**Solution: **

The correct option is (D).

The given vectors are in the ratio 3: 1

**21. The vector having initial and terminal points as (2, 5, 0) and (â€“3, 7, 4), respectively is **

**Solution:**

The correct option is (C).

Let A and B be two points whose coordinates are given as (2, 5, 0) and (-3, 7, 4)

So, we have

**22. The angle between two vectors and with magnitudes âˆš3 and 4, respectively, and is **

**Solution: **

The correct option is (B).