| A | B |
|---|
| line | extends forever in both directions |
| segment | has two endpoints |
| ray | has one endpoint and extends forever in the other direction |
| endpoint | a point which shows a where a segment or ray ends |
| intersecting lines | lines that cross |
| nonintersecting lines | lines that do not cross, but are not parallel |
| perpendicular lines | lines that intersect to form a right angle |
| parallel lines | lines that will not intersect no matter how far they are extended |
| angle | formed when two lines intersect |
| vertex | the point where two lines intersect to form an angle |
| acute angle | an angle smaller than a right angle |
| obtuse angle | an angle larger than a right angle but smaller than a straight angle |
| straight angle | a 180 degree angle |
| right angle | a 90 degree angle |
| degree | a unit used to measure angles |
| complementary angles | two angles that have a sum of 90 degrees |
| supplementary angles | two angles that have a sum of 180 degrees |
| protractor | a tool used to measure angles |
