Editing Inversive geometry (section)

===== Point inside circle =====
To construct the inverse ''P'' of a point ''P{{'}}'' inside a circle ''Ø'':
* Draw ray ''r'' from ''O'' (center of circle ''Ø'') through ''P{{'}}''. (Not labeled, it's the horizontal line)
* Draw line ''s'' through ''P{{'}}'' perpendicular to ''r''. (Not labeled. It's the vertical line)
* Let ''N'' be one of the points where ''Ø'' and ''s'' intersect.
* Draw the segment ''ON''.
* Draw line ''t'' through ''N'' perpendicular to ''ON''.
*  ''P'' is where ray ''r'' and line ''t'' intersect.