| A | B |
|---|
| point | an exact location in space |
| line | a straight path that extends without end in opposite directions |
| ray | a part of a line that starts at one endpoint and extends forever |
| line segment | a part of a line that extends from one endpoint to another |
| plane | a perfectly flat surface that extends infinitely in all directions |
| congruent | having the same shape and size |
| angle | a figure formed by two rays with a common endpoint |
| vertex | the point where two sides intersect |
| right angle | an angle that measures exactly 90 degrees |
| acute angle | an angle that measures less than 90 degrees |
| obtuse angle | an angle that measures more than 90 degrees |
| straight angle | an angle that measures exactly 180 degrees |
| complementary angles | two angles whose measures add to 90 degrees |
| supplementary | two angles whose measures add to 180 degrees |
| perpendicular lines | two lines that intersect two form right angles |
| parallel lines | lines that do not intersect |
| skew lines | lines that lie in different planes, and are neither parallel nor intersecting |
| vertical angles | opposite angles formed by two intersecting lines |
| transversal | a line that intersects two or more lines |
| circle | the set of all points in a plane that are the same distance from a given point |
| center of a circle | the point inside a circle that is the same distance from all the points on the circle |
| radius | line segment whose endpoints are the center of the circle and any point on the circle |
| diameter | line segment that passes through the center of the circle and whose endpoints lie on the circle |
| chord | line segment whose endpoints are any two points on the circle |
| arc | part of a circle named by its endpoints |
| central angle | an angle with its vertex at the center of a circle |
| sector | a part of a circle enclosed by two radii and an arc connecting them |
