Hi everyone, anyone fancy helping out on yet another question

A complex number is represented by the point P on an Argand diangram, .

a. Sketch the locus of P.

This I could do, circle, centre (5, 12), radius of 3.

b. Find the maximum and minimum values for .

For this I found the distance of the centre of the circle from the origin, and then the radius to get 10 and 16, is this correct?

c. Find the min and max values for in radians to 2dp.

Argument is , but not sure where to go to get the max and min values from here?

Thanks in advance