| A | B |
|---|
| Right Angle | The name of an angle that measures exactly 90 degrees |
| Straight Angle | The name of an angle that measures exactly 180 degrees |
| Acute Angle | An angle that measures less than 90 degrees |
| Obtuse Angle | An angle that measures between 90 and 180 degrees |
| Protractor | A tool used to measure angles |
| Vertex | The endpoint where two rays meet, forming an angle |
| 180 degrees | 1/2 of a circle |
| Degrees | The unit that angles are measured by |
| 60 degrees | 1/6 of a circle |
| 90 degrees | 1/4 of a circle equal ? degrees |
| 36 degrees | 1/10 of a circle |
| 120 degrees | 1/3 of a circle |
| 72 degrees | 1/5 of a circle |
| 40 degrees | 1/9 of a circle |
