Cylindrical Coordinates

* why is there ρ in graph (from where came)?

*what is difference between "ρ0" and "ρ" ?

 

ρ is the radial coordinate. ρ0 is a particular constant value of the radial coordinate at which a differential length or differential area is computed.

\(\rho=\sqrt{x^2 + y^2}\)

As shown in the diagram the cylindrical coordinates are ρ, φ, and z