1. Click to reveal two points P and Q;
2. Click for a plane on the line PQ;
3. Move the slider? How many planes go through two points;
4. Click to reveal a third point A;
5. Move the slider so that the orangle plane contains the three points P, Q and A;
6. Click to reveal plane that contains the three points P, Q and A;
How many points are needed to define a particular plane?