- #1

- 717

- 20

we get

[tex]\vec{e}_{\rho}=\frac{\frac{\partial \vec{r}}{\partial \rho}}{|\frac{\partial \vec{r}}{\partial \rho}|}[/tex]

[tex]\vec{e}_{\varphi}=\frac{\frac{\partial \vec{r}}{\partial \varphi}}{|\frac{\partial \vec{r}}{\partial \varphi}|}[/tex]

Is it correct for any orthogonal system or maybe for any system? Why you can use this relation?