How to Convert Spherical Coordinates to Cartesian Coordinates in an Equation?

[Philosophaie]

I have an equation:

Br*r + BƟ*Ɵ

BØ = 0

I want to change it into x,y,z. How do I do this?

x=r*cosƟ*sinØ = 0
y=r*sinƟ*sinØ = 0
z=r*cosØ = r

?

 

[HallsofIvy]

Is B a constant? If so then we have \phi= 0 which means we are on the z-axis and \theta becomes irrelevant. \vec{r}, the unit vector pointing directly away from the origin must be <0, 0, 1> "Br*]b]r[/b] + BƟ*Ɵ" becomes just <0, 0, Bz>.