| A | B |
|---|
| triangle | 3 straight sides and 3 angles |
| quadrilateral | 4 sides and 4 angles |
| pentagon | 5 sides and 5 angles |
| hexagon | 6 sides and 6 angles |
| octagon | 8 sides and 8 angles |
| decagon | 10 sides and 10 angles |
| angle | figure formed by two rays which have the same endpoint |
| vertex | the common endpoint of the sides of an angle |
| right angle | an angle that forms a square corner |
| right angle | measures 90 degrees |
| acute angle | an angle that is less than a right angle |
| acute angle | measures less than 90 degrees |
| obtuse angle | an angle that is greater than a right angle |
| obtuse angle | measures more than 90 degrees |
| straight angle | an angle whose rays point in exactly opposite directions |
| straight angle | measures 180 degrees |
| perpendicular lines | intersect to form right angles |
| point | an exact location in space |
| line | a straight path that goes on forever in two directions |
| line segment | part of a line |
| ray | has one endpoint and goes on forever in one direction |
| intersecting lines | meet or cross each other |
| parallel lines | never intersect |
