View source for Pole

{{TEX|done}}
The pole of coordinates is the origin in [[Polar coordinates|polar coordinates]].

A pole is the centre of an [[Inversion|inversion]].

The pole of the straight line $p$ with respect to a [[Conic|conic]] is the point $P$ such that the line $p$ is the [[Polar|polar]] of the point $P$ with respect to the conic.



====Comments====
For poles of (analytic) functions see [[Pole (of a function)|Pole (of a function)]]. Sometimes the word  "pole"  is used for the point $(0,0,1)$ (North pole) or $(0,0,-1)$ (South pole) of the unit sphere in $\mathbf R^3$, with centre at the origin.

====References====
<table><TR><TD valign="top">[a1]</TD> <TD valign="top">  M. Berger,   "Geometry" , '''1–2''' , Springer  (1987)  (Translated from French)</TD></TR><TR><TD valign="top">[a2]</TD> <TD valign="top">  H.S.M. Coxeter,   "Introduction to geometry" , Wiley  (1963)</TD></TR></table>