| A | B |
|---|
| Geometric reasoning | Looking for patterns, making a conjecture, and verifying the conjecture. |
| Undefined terms | Point, line, and plane. |
| Segment | Consists of two endpoints and all points that lie on the line between those endpoints. |
| Ray | Consists of an initial point and all points on the line that lay on either one side of the endpoint or the other. |
| Collinear | Points, segments, or rays that lie on the same line. |
| Angle | Two different rays that have the same initial point. |
| Acute | An angle whose measure is between 0 and 90 degrees. |
| Right | An angle whose measure is exactly 90 degrees. |
| Obtuse | An angle whose measure is between 90 and 180 degrees. |
| Straight | An angle whose measure is exactly 180 degrees. |
| Reflex | An angle whose measure is between 180 and 360 degrees. |
| Interior | A point that lies between points that lie on each side of an angle. |
| Exterior | A point that does not lie in the interior of an angle, or on the angle. |
| Adjacent | Two angles that share a common vertex and side, but have no common interior points. |
| Postulates | Rules in geometry which must be accepted as true without proof; also called axioms. |
| Ruler Postulate | The points on a line can be matched one-to-one with the set of real numbers, which allows you to determine the coordinate of a point and the distance between points. |
| Segment Addition Postulate | If B is between A and C, then AB+BC=AC. |
| Protractor Postulate | The rays that form an angle can be put in one-to-one correspondence with the real numbers between 0 and 180 degrees inclusive, which allows angles to be measured. |
| Angle Addition Postulate | Allows you to add the measures of adjacent angles. |
| Congruent | Two segments or angles having the same measure. |
| Midpoint | The point that divides a segment into two congruent segments. |
| Segment bisector | A segment, ray, line, or plane that intersects a segment at its midpoint. |
| Angle bisector | A ray that divides an angle into two congruent angles. |
| Perpendicular | Two lines that intersect to form a right angle. |
| Distance formula | A formula used to calculate the distance between two points in a coordinate plane. |
| Hypothesis | In a conditional statement, the part following the "if" denoted by "p". |
| Conclusion | In a conditional statement, the part following the "then" denoted by "q". |
| Conditional statement | A logical statement that can be written in "if-then" form. |
| Converse | A conditional statement formed by interchanging the hypothesis and conclusion. |
| Counterexample | One example used to demonstrate that a conditional statement is false. |
| Biconditional statement | A true conditional statement whose converse is also true. |
| Reflexive | Any geometric object is congruent to itself. |
| Symmetric | If one geometric object is congruent to a second, then the second is congruent to the first. |
| Transitive | If one geometric object is congruent to a second, and the second is congruent to a third, then the first object is congruent to the third object. |
| Vertical angles | Two angles whose sides form two pairs of opposite rays. |
| Linear pair | Two adjacent angles whose noncommon sides are opposite rays. |
| Complementary | Two angles whose measures sum to 90 degrees. |
| Supplementary | Two angles whose measures sum to 180 degrees. |
| Linear Pair Postulate | If two angles form a linear pair, then they are supplementary. |
| Vertical Angles Theorem | If two angles are vertical angles, then they are congruent. |
| Congruent Supplements Theorem | If two angles are supplementary to the same angle or to congruent angles, then they are congruent. |
| Congruent Complements Theorem | If two angles are complementary to the same angle or to congruent angles, then they are congruent. |
| Deductive reasoning | To reason from known facts; used when proving a theorem. |
