Question

how to calculate magnitude?

Answer 1

Magnitude of a vector means only physical value without direction.
Let A vector
$$\begin{gathered} A=a\hat{i}+b\hat{j}+c\hat{k}\left(\hat{i},\hat{j}and\hat{k}beunitvectorsalongxyandzdirection\right) \\ \left|A\right|=\sqrt{a^2+b^2+c^2} \end{gathered}$$