Describe the three rigid motions? why are they called rigid motions?

Rigid Motions are any way of moving all the points in a plane such that
a) the relative distance between points says the same and
b) the relative position of the points stays the same.

The three rigid motions are
1) Translation - everything is moved by the same amount and in the same direction.
2) Rotation - A rotation fixes one point and everything rotates by the same amount around that point.
3) Reflection - fixes a mirror line in the plane and exchanges points from one side of the line with points on the other side of the mirror at the same distance from the mirror. Every reflection has a mirror line.

They are called rigid motions because of the way they move on a plane.

Hope all of this helped!! :)

Ithink it's the first one ( let me know if it right)