Question

$\vec{k}\cdot \vec{k}=$

1. 1
2. 0
3. 2
4. -1

Answer: 1

Solution :-

We know that $\vec{i},\vec{j}\text{and}\vec{k}$ are unit vector in the direction of $x,y\text{and}z-axis$ respectively.
Hence, $\mid \vec{i}\mid =\mid \vec{j}\mid =\mid \vec{k}\mid =1\cdot$

And, also We know that the angle between any position vector with itself is 0.

So, correct answer is option-1, $\to 1$