Plane is an undefined plane
Hi, there are three undefined terms in geometry: point, line, and plane.
Point: has no size, only location . It can be named with a capital letter.
Plane: a flat surface that has no thickness, that extends infinitely n every direction. Is named by a single letter or by three coplanar, but non-collinear, points.
Line: Set of points extending in either direction infinitely.
Angle, circle, and ray are not undefined terms. are not Plane.