* Plane: A perfectly flat surface that has no thickness and extends forever in two directions.
* Line: A straight path of points that extends forever in two directions. A line does not have any width or thickness. The word line is often used to indicate a line segment or a ray.
* Line segment: The set of points on a line between any two points on the line, basically just a piece of a line from one point to another that contains all the points in between.
| Intersecting straight lines determine a point | /
/
--------x-------
/
/
|
| Two points on a line determine a line | -------x-------x-------- |
| Three points on a plane determine a plane | _______________
/ x /
/ /
/ x /
/ x /
/______________/
|
| Two intersecting lines on a plane determine a plane | _______________
/ \ /
/ \ /
/ -----\----- /
/ \ /
/__________\___/
|
| A line and a point not on the line determine a plane | _______________
/ \ /
/ \ * /
/ \ /
/ \ /
/__________\___/
|
| The intersection of a line and a plane is a point (unless the line and plane are parallel or coincide) | \
__\ __________
/ \ /
/ \ /
/ *P /
/_____________/
|
| The intersection of two planes is a line (unless the planes are parallel or coincide) | ___ ______________
\ / /
\ / /
X-------------X
/_\_ _ _ _ _ _/ \
\_____________\
|
| The intersection of three planes is a point (unless some planes are parallel or coincide) | _________
__ |_________|____
\ / /| /
\ / / | /
X--------* |-X
/_\ \ | \
\________\|___\
|_________|
|
