# NCERT Class 12-Mathematics: Chapter – 10 Vector Algebra Part 5 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 20**:

The unit vector perpendicular to the vectors and forming a right handed system is

(A)

(B)

(C)

(D)

**Answer**:

(A) Is the correct answer.

Required unit vector is .

**Question 21**:

If then lies in the interval

(A)

(B)

(C)

(D)

**Answer**:

(A) Is the correct answer.

The smallest value of will exist at numerically smallest value of . , at , which gives

The numerically greatest value of is at which

## 10.3 EXERCISE

### Short Answer (S. A)

**Question 1**:

Find the unit vector in the direction of sum of vectors

**Answer**:

Let

**Question 2**:

If find the unit vector in the direction of

(i)

(ii)

**Answer**:

Here,

(i) Since,

(ii) Since,

**Question 3**:

Find a unit vector in the direction of , where P and Q have co-ordinates and , respectively.

**Answer**:

Since, the coordinates of are and , respectively.

**Question 4**:

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

**Answer**:

**Question 5**:

Using vectors, find the value of *k* such that the points and are collinear.

**Answer**:

**Question 6**:

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

**Answer**: