Inversion of a circle and a line

Inversion of a circle

The fixed white circle is the circle of inversion. The blue circle is variable.
This page requires a Java capable browser. 1. Move the point C counter-clockwise, how is C' moving?

Is your answer valid for every position of the blue circle?

Give a general rule.




This page requires a Java capable browser. 2. Keep the white circle of inversion fixed.
How many circles (the blue ones) of center A are globally invariant?



This page requires a Java capable browser. 3. Let the radius of the circle around A be fixed.
How many circles of this radius are globally invariant?



This page requires a Java capable browser. 4. The radius of the white circle of inversion is k and the radius of the blue inversed circle is r.
Where are the centers of the globally invariant circles of Problem 3 above?



Inversion of a line

This page requires a Java capable browser. 5. When D is moving on the line, D' is moving on the black circle. In your own meaning, what does it mean that D is moving in the positive sense?

How is D' moving when D is moving in the positive sense?




Find suitable circles of inversion

This page requires a Java capable browser. 6. For a given blue line and a given blue circle, try to choose the white circle of inversion in such a way that

a) D' is on the circle,
b) D is on a black line (transformed from an originally black circle) and
c) both black lines are simultaneously on top of the blue ones.

Try to solve the problem in the three relative positions of the blue line and the blue circle.

What are the 3 possible relative positions?




This page requires a Java capable browser. 7. Given a line g and a circle G, is it always possible to find an inversion f such that f(g) = G?