I thought I would write a computer routine to check if two figures were congruent by the CCSS definition (rigid motions). One day I will post it.
The most important thing was to be specific as to what is a geometrical figure. You can read the CCSS document from front to back, back to front, upside down and more, but NO DEFINITION of a geometrical figure. For the computer program I decided that a geometrical figure was simply a set of points. My diagram may show some of them joined, but any two points describe a line segment (or a line). So a line segment “exists” for any pair of points.
The question is “Are the two figures shown below congruent or not?
I rest my case…..