Circle inversion
From JSXGraph Wiki
The point [math]\displaystyle{ P' }[/math] is the result of a circle inversion of [math]\displaystyle{ P }[/math] on circle [math]\displaystyle{ c }[/math] (black circle line).
The point [math]\displaystyle{ P' }[/math] is the result of a circle inversion of [math]\displaystyle{ P }[/math] on circle [math]\displaystyle{ c }[/math] (black circle line).