In sphereical coordinates you know that [itex]x=\rho\cos\theta\sin\phi[/itex], [itex]y=\rho\sin\theta\sin\phi[/itex] and [itex]z=\rho\cos\phi[/itex]
You can use this to find limits for [itex]\rho[/itex].
If you draw the x-z or y-z plane intercept this can help you find [itex]\phi[/itex]