1.1 Understanding Points, Lines and Planes
Point: Location without size
Line: Straight path without thickness, extends forever
Plane: Flat surface without thickness, extends forever
Segment: Part of line consisting of two points, and all points in between
Endpoint: A point at one end of a segment or the starting point of a ray
Ray: Part of a line that starts at an endpoint and extends forever in one direction
Opposite Ray: 2 rays that have a common endpoint
Postulate 1-1-1 Through any 2 points, there is exactly one line
Postulate 1-1-2 Through any 3 non-colinear points, there is exactly one plane containing them
Postulate 1-1-3 If 2 points lie in a plane, then the line containing those points lies in the plane
Postulate 1-1-4 If 2 lines intersect, then they intersect at exactly one point
Postulate 1-1-5 If 2 planes intersect, they do so at one line
Line: Straight path without thickness, extends forever
Plane: Flat surface without thickness, extends forever
Segment: Part of line consisting of two points, and all points in between
Endpoint: A point at one end of a segment or the starting point of a ray
Ray: Part of a line that starts at an endpoint and extends forever in one direction
Opposite Ray: 2 rays that have a common endpoint
Postulate 1-1-1 Through any 2 points, there is exactly one line
Postulate 1-1-2 Through any 3 non-colinear points, there is exactly one plane containing them
Postulate 1-1-3 If 2 points lie in a plane, then the line containing those points lies in the plane
Postulate 1-1-4 If 2 lines intersect, then they intersect at exactly one point
Postulate 1-1-5 If 2 planes intersect, they do so at one line
