If this sound like a dumb question I'm sorry.

The Problem, find a set of spherical coordinates of the point whose Cartesian points are given.

( 0, sqrt 3, 1)

The first point is the square root of the sums of the squares of x, y, and z. No problem. The first point is 2

The second point is the inverse tangent of the square root of the sum of the squares of x and y divided by z

Again no problem, the second point is pi/3

Here is the problem, the final point is the inverse tangent of y/x. x is 0 what do I do now?