**NCERT Solutions for Maths Class
12 Exercise 10.4**

Hello Students. Welcome to **maths-formula.com**. In this post, you will find the complete** ****NCERT Solutions for Maths Class 12 Exercise 10.4**.

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Class 12th is a very crucial stage of your student’s life, since you take all important decisions about your career on this stage. Mathematics plays a vital role to take decision for your career because if you are good in mathematics, you can choose engineering and technology field as your career.

**NCERT Solutions for Maths Class 12 Exercise 10.4** helps you to solve each and every problem with step by step explanation which makes you strong in mathematics.

All the schools affiliated with CBSE, follow the NCERT books for all subjects. You can check your syllabus from **NCERT Syllabus for Mathematics Class 12**.

**NCERT Solutions for Maths Class 12 Exercise 10.4** are prepared by the experienced teachers of CBSE board. If you are preparing for JEE Mains and NEET level exams, then it will definitely make your foundation strong.

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**NCERT Solutions for Maths Class 12 Exercise 10.1**

**NCERT Solutions for Maths Class 12 Exercise 10.2**

**NCERT Solutions for Maths Class 12 Exercise 10.3**

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**NCERT Solutions for Maths Class 12 Exercise 10.4**

**Maths Class
12 Ex 10.4 Question 1.**

Find |** a** ×

**|, if**

*b***=**

*a***– 7**

*i***+ 7**

*j***and**

*k***= 3**

*b***– 2**

*i***+ 2**

*j***.**

*k***Solution:**

We have given that, ** a** =

**– 7**

*i***+ 7**

*j***and**

*k***= 3**

*b***– 2**

*i***+ 2**

*j*

*k***Maths Class
12 Ex 10.4 Question 2.**

Find a unit vector perpendicular to each of the vector ** a**
+

**and**

*b***–**

*a***, where**

*b***= 3**

*a***+ 2**

*i***+ 2**

*j***and**

*k***=**

*b***+ 2**

*i***– 2**

*j***.**

*k***Solution:**

We have given that, ** a** = 3

**+ 2**

*i***+ 2**

*j***and**

*k***=**

*b***+ 2**

*i***– 2**

*j*

*k*Therefore,

**+**

*a***= (3**

*b***+ 2**

*i***+ 2**

*j***) + (**

*k***+ 2**

*i***– 2**

*j***) = 4**

*k***+ 4**

*i*

*j*And ** a** –

**= (3**

*b***+ 2**

*i***+ 2**

*j***) – (**

*k***+ 2**

*i***– 2**

*j***) =**

*k***+ 4**

*i*

*k***Maths Class
12 Ex 10.4 Question 3.**

If a unit vector ** a** makes
angles Ï€/3 with

**, Ï€/4 with**

*i***and an acute angle Î¸ with**

*j***, then find Î¸ and hence the components of**

*k***.**

*a***Solution:**

Let ** a** =

*a*_{1}

**+**

*i*

*a*_{2}

**+**

*j*

*a*_{3}

**such that**

*k***= 1**

*a***Maths Class
12 Ex 10.4 Question 4.**

Show that (** a** –

**) × (**

*b***+**

*a***) =**

*b***2**(

**×**

*a***)**

*b*

**Solution:**

**Maths Class
12 Ex 10.4 Question 5.**

**Solution:**

**Maths Class
12 Ex 10.4 Question 6.**

Given that ** a**.

**= 0 and**

*b***×**

*a***= 0. What can you conclude about the vectors**

*b***and**

*a***?**

*b***Solution:**

**Maths Class
12 Ex 10.4 Question 7.**

Let the vectors ** a**,

**,**

*b***be given as**

*c*

*a*_{1}

**+**

*i*

*a*_{2}

**+**

*j*

*a*_{3}

**,**

*k*

*b*_{1}

**+**

*i*

*b*_{2}

**+**

*j*

*b*_{3}

**,**

*k*

*c*_{1}

**+**

*i*

*c*_{2}

**+**

*j*

*c*_{3}

**. Then show that**

*k***× (**

*a***+**

*b***) =**

*c***×**

*a***+**

*b***×**

*a***.**

*c***Solution:**

**Maths Class
12 Ex 10.4 Question 8.**

If either ** a** = 0 or

**= 0, then**

*b***×**

*a***= 0. Is the converse true? Justify your answer with an example.**

*b***Solution:**

**Maths Class
12 Ex 10.4 Question 9.**

Find the area of the triangle with vertices A(1, 1, 2), B(2, 3, 5)
and C(1, 5, 5).

**Solution:**

**Maths Class
12 Ex 10.4 Question 10.**

Find the area of the parallelogram whose adjacent sides are
determined by the vectors ** a** =

**–**

*i***+ 3**

*j***and**

*k***= 2**

*b***– 7**

*i***+**

*j***.**

*k***Solution:**

**Maths Class
12 Ex 10.4 Question 11.**

Let the vectors ** a** and

**be such that |**

*b***| = 3 and |**

*a***| = √2/3, then**

*b***×**

*a***is a unit vector, if the angle between**

*b***and**

*a***is**

*b*(A) Ï€/6 (B) Ï€/4 (C) Ï€/3 (D) Ï€/2

**Solution:**

We have given that

Hence, the correct answer is option (B).

**Maths Class
12 Ex 10.4 Question 12.**

Area of a rectangle having vertices A, B, C and D with position vectors , respectively is

(A) ½ (B) 1 (C) 2 (D) 4

**Solution:**