| A | B |
|---|
| collinear | on the same line |
| noncollinear | not on the same line |
| point | undefined term - represented by a "dot", no dimension, named with a capital letter |
| line | undefined term, extends forever in 2 directions, straight, no thickness, determined by 2 points |
| plane | undefined term, a flat surface that extends forever, has no thickness, determined by 3 noncollinear points |
| coplanar | on the same plane |
| noncoplanar | not on the same plane |
| intersection of two figures | the set of points that are in both figures |
| the segment addition postulate | If B is between A and C as a picture: A-----B----C, then AB + BC = AC |
| midpoint | A point that divides a segment into two congruent segments |
| congruent figures | figures that have the same size and shape |
| congrent segments | segments that are equal in length |
| segment bisector | a segment, line or plane that intersects a segment at its midpoint |
| How many points determine a plane? | 3 noncollinear |
| How many points determine a line? | 2 |
| How many points determine space? | 4 noncoplanar |
| How many planes can contain 3 collinear points? | Infinitely many |
| Do two planes always intersect? | No |
| How many lines can pass through one point? | Infinitely many |
| Ray | has one endpoint, extends in one direction infinitely |
| opposite rays | 2 rays that share the same endpoint and form a line |
| angle | a figure formed by 2 rays that have the same endpoint |
| straight angle | an angle whose measure is 180 degrees |
