Mathematical Tools

Hint: \(\hat A=\dfrac{\vec A}{|\vec A|}\)

Step: 

Find the unit vector in the direction of \(\vec A.\)
A unit vector is obtained by dividing the vector by its magnitude.
Given, \(|\vec A| = A\)
Therefore, \(\hat A=\dfrac{\vec A}{|\vec A|}\)
Hence, option (4) is the correct answer.