| A | B |
|---|
| Collinear | Points that lie on the same line. |
| Noncollinear | Points that lie DO NOT lie on the same line. |
| Three undefined terms | Points, lines, and planes |
| Coplanar | Points that lie on the same plane. |
| segment | Piece of a line that has a starting point and an ending point. |
| betweenness | A point can be anywhere between two other points. |
| Congruent Segments | Segments that have the same length. |
| Midpoint | The point between two other points that creates two equal segments. |
| Segment Bisector | Anything that divides a segment into two equal parts. |
| Segment Addition Postulate | If B is between A and C, then AB + BC = AC |
| Midpoint Theorem | If the M is the midpoint of PQ, then PM is congruent to MQ |
| Angle | Formed by two rays that have a common endpoint |
| Right Angle | An angle whose measure is 90. |
| Acute Angle | An angle whose measure is less than 90. |
| Obtuse Angle | An angle whose measure is greater than 90 but less than 180. |
| Straight Angle | An angle whose measure is 180 |
| Congruent Angles | Angles that have the same measure. |
| Angle Bisector | A ray that divides an angle into two congruent angles. |
| Perpendicular Lines | Two intersecting lines that form four right angles. |
| Adjacent Angles | Angles that are next to each other. |
| Vertical Angles | Angles that are opposite each other when lines intersect. |
| Linear Pair | Two angles that form a line. |
| Complimentary Angles | Two angles whose sum is 90. |
| Supplementary Angles | Two angles whose sum is 180. |
