| A | B |
|---|
| right angle | Measures exactly 90 degrees. |
| acute angle | Measures greater than 0 degrees, less than 90 degrees |
| obtuse angle | Measures greater than 90 degrees and less than 180 degrees |
| right triangle | Has one right angle. |
| obtuse triangle | Has one obtuse angle. |
| acute triangle | Has 3 acute angles. |
| protractor | Tool used to measure angles. |
| point | An exact location in space. |
| line | A collection of points that go on and on in both directions. It has no endpoints. |
| line segment | Part of a line. It has 2 endpoints and includes all the points between those endpoints. |
| ray | part of a line. It has one endpoint and continues on and on in one direction. |
| vertex | The endpoint of two rays. |
| intersecting lines | Lines that cross and have one point in common. |
| perpendicular lines | Intersecting lines that form right angles where they intersect. |
| parallel lines | Lines that lie on the same flat surface and never cross. |
