| A | B |
|---|
| point | An exact location in space. |
| line | An endless collection of points along a straight path. It has no endpoints. |
| line segment | A part of a line having two endpoints. |
| ray | A part of a line that has one endpoint and goes on and on in one direction. |
| plane | An endless flat surface that is named by any three points not on the same line. |
| intersecting lines | Lines that have exactly one point in common. |
| parallel lines | Lines in the same plane that NEVER intersect. |
| perpendicular lines | Two lines that intersect at right angles. |
| angle | Two rays with a common endpoint. |
| acute angle | An angle with a measure LESS than 90 degrees. |
| obtuse angle | An angle with a measure MORE than 90 degrees. |
| right angle | An angle that measures EXACTLY 90 degrees. |
| straight angle | An angle that measures EXACTLY 180 degrees. |
| angle ruler OR protractor | An INSTRUMENT used to measure or draw angles. |
| degree | A UNIT for measuring angles. |
| circle | A closed plane figure. All the points are the same distance from a point called the center. |
| center | The POINT from which all points on a circle are equally distant. |
| chord | A line segment with both endpoints on the circle. |
| circumference | The distance around a circle. |
| diameter | A line segment that passes through the center of a circle and has both endpoints on the circle. |
| radius | A line segment with one endpoint on the circle and the other endpoint at the center. |
