# NCERT Class 12-Mathematics: Chapter –10 Vector Algebra Part 5

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Question 20:

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

(A)

(B)

(C)

(D)

Required unit vector is .

Question 21:

If then lies in the interval

(A)

(B)

(C)

(D)

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

Question 1:

Find the unit vector in the direction of sum of vectors

Let

Question 2:

If find the unit vector in the direction of

(i)

(ii)

Here,

(i) Since,

(ii) Since,

Question 3:

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

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 .

Question 5:

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