# Vector Algebra Lecture 3 Class 12 Maths

## Lecture - 3 Chapter 10 Vector Algebra

Whether you are waking up early to go to work, school, or just running some errands, it’s important that you spend a few minutes to sharpen your mind, fill your heart, and think positively so that you can start the day off feeling blessed with a grateful heart.

In this video I am discussing about Direction Cosines and Direction angles.

 NCERT EXERCISE 10.2

2. Write two different vectors having same magnitude.

3. Write two different vectors having same direction.

4. Find the values of x and y so that the vectors $2\hat{i}+3\hat{j}$ and $x\hat{i}+y\hat{j}$ are equal.

5. Find the scalar and vector components of the vector with initial point (2, 1) and terminal point (– 5, 7).

7. Find the unit vector in the direction of the vector $\vec{a}=\hat{i}+\hat{j}+2\hat{k}$

8. Find the unit vector in the direction of vector $\vec{PQ}$, where P and Q are the points (1, 2, 3) and (4, 5, 6), respectively.

11. Show that the vectors $2\hat{i}-3\hat{j}+4\hat{k}$ and $-4\hat{i}+6\hat{j}-8\hat{k}$ are collinear.

12. Find the direction cosines of the vector $\hat{i}+2\hat{j}+3\hat{k}$

13. Find the direction cosines of the vector joining the points A(1, 2, –3) and B(–1, –2, 1), directed from A to B.

14. Show that the vector $\hat{i}+\hat{j}+\hat{k}$ is equally inclined to the axes OX, OY and OZ.