|
 point | a location in space; it has no size |
| line | a series of points that extends in opposite directions without end |
| plane | a flat surface with no thickness. It contains many lines and extends without end in the directions of all its lines |
| segment | part of a line; it has two endpoints. |
| ray | part of a line; it has exactly one endpoint. Name its endpoint first |
| parallel lines | two lines that lie in the same plane and have no points in common |
| intersecting lines | lines that lie in the same plane and have exactly one point in common |
| skew lines | lines that lie in different planes; they are not parallel and do not intersect |
| acute angle | an angle that is less than 90˚ |
| obtuse angle | an angle that is greater than 90˚ and less than 180˚ |
| straight angle | an angle that is equal to 180˚ |
| right angle | an angle that is equal to 90˚ |
| adjacent angles | angles that share a vertex and a side but have no points in their interiors |
| vertical angles | angles formed by two intersecting lines and are opposite each other. The opposite angles have the same measure |
| supplementary angles | the sum of the measure of two angles equals 180˚ |
| complementary angles | the sum of the measure of two angles equals 90˚ |
| transversal | a line that intersects two other lines in different points |
| corresponding angles | angles that lie on the same side of the tranversal and in the same relative position |
| alternate interior angles | angles between a pair of lines and on the opposite sides of the transversal |
| vertex | the point of intersection of two sides of an angle or figure |
| perpendicular lines | lines that intersect to form right angles |