Inversion in a Cirlce
Inversion in a Circle is when a point inside the circle (K) is reflected upon the circle, thus, creating a fixed point outside the circle (K').
There are few spots where K cannot be reflected:
When K is at O, the center, this is because K would be equidistant to every part of the circle and there could not be a single point of reflection.
Also, when K is on the circle itself, the reflection, K', is at the same spot as K.
Equation: OK * OK' = r^2