Question

Which of the following statements are correct regarding dot product of vectors?
1. Dot product is less than or equal to the product of magnitudes of two vectors.
2. When two vectors are perpendicular to each other,then their dot product is non-zero.
3. Dot product of two vectors is positive or negative depending whether the angle between the vectors is less than or greater than $\frac{\pi }{2}$.
4. Dot product is equal to the product of one vector and the proection of the vector on the first one.
select the correct answer using the codes given below

• A. 1,2 and 3 only
• B. 1,3 and 4 only
• C. 1,2 and 4 only
• D. 2,3 and 4 only

Answer 1

The correct option is B 1,3 and 4 only

Dot product is given by
$\overrightarrow{A}.\overrightarrow{B}=\left|A\right|\left|B\right|cos\theta$
where $\theta$ is angle between the vector A & B.
Also

So dot product is product of one vector and the projection of the other vector on the first vector.