| A | B |
|---|
| point | basic unit of geometry |
| line | a straight arrangement of points |
| plane | has length and width but no thickness |
| space | the set of all points |
| segment | two points and all the points between them that lie onthe line containing the two points |
| endpoint | two important points of a segment |
| ray | part of a line that starts at an endpoint and continues forever in one direction |
| angle | two rays that share a common endpoint |
| vertex | the common endpoint of two rays that make an angle |
| sides | two rays of an angle |
| degree | unit of measure for angles |
| counter-example | an examploe that proves a statement wrong |
| right angle | an angle whose measure is 90 |
| acute angle | an angle whose measure is less than 90 |
| obtuse angle | an angle whose measure is greater than 90 |
| midpoint of a segment | a point equal distant from each endpoint |
| angle bisector | ray that divides an angle in two equal parts |
