Math Help - Sombrero function

1. Sombrero function

What class of functions can be defined "sombrero function" ?
Can I write the classic sombrero function $f(r,\theta) = \frac{sin(r)}{r} \quad for \quad r\neq0$
in rectangular expression ? $f(x,y) = \frac{sin(\sqrt{x^2+y^2})}{\sqrt{x^2+y^2}} \quad for \quad x^2+y^2\neq0$

Thanks

2. Yes, that's perfectly correct.