| plane | a flat surface of points that goes on forever in all directions |
| complementary angles | two angles whose sum measures 90 degrees |
| line segment | an infinite number of points that has two distinct end points |
| supplementary | two angles whose sum measures 180 degrees |
| ray | an infinite set of points that starts at a point and goes on forever |
| obtuse angle | an angle whose measure is greater than 90 degrees and less than 180 |
| bisect | to cut into two congruent parts |
| line | an infinite number of points that goes on forever in both directions |
| acute angle | an angle whose measure is greater than 0 degrees and less than 90 degrees |
| right angle | an angle formed by two perpendicular lines, the measure of which is 90 degrees |
| straight angle | an angle whose measure is 180 degrees |
| vertex | the point of intersection of the two rays that form the sides of the angle |
| angle | a geometric figure formed by two rays that have a common endpoint |
| collinear | points that lie on the same line |
| coplanar | any three or more points that lie in the same plane |
| perpendicular | lines that intersect to form right angles |
| congruent | having the same size and shape |
| point | a location in space (it has no dimensions) |
| midpoint | The point that divides a segment into two congruent segments. |
| intersect | to meet at a point |