| Term | Definition |
|---|
| line | A straight path in a plane that goes on forever in opposite directions |
| ray | A part of a line, with one endpoint, that continues without end in one direction |
| parallel lines | Lines in a plane that never intersect |
| intersecting lines | Lines that cross at exactly one point |
| perpendicular lines | Two lines that intersect to form four right angles |
| angle | A figure formed by two rays that have a common endpoint |
| acute angle | An angle that has a measure greater than 0° and less than 90° |
| right angle | An angle formed by perpendicular lines, line segments, or rays that has a measure of 90° |
| obtuse angle | An angle whose measure is greater than 90° and less than 180° |
| straight angle | An angle whose measure is 180° |
| vertex | The point where two or more rays meet; the point of intersection of two sides of a polygon; the point of intersection of three or more edges of a solid figure; the top point of a cone; the plural of vertex is vertices |
| complementary angles | Two angles whose measures have a sum of 90° |
| supplementary angles | Two angles whose measures have a sum of 180° |
| triangle | A polygon with three sides |
| scalene triangle | A triangle with no congruent sides |
| quadrilateral | A polygon with four sides |
| pentagon | A polygon with five sides |
| hexagon | A polygon with 6 sides |
| octagon | A polygon with 8 sides |
| parallelogram | A quadrilateral whose opposite sides are parallel and congruent |
| degree | A unit of measurement to measure angles |
| dodecagon | A polygon with 12 sides |
| heptagon | A polygon with 7 sides |
| point | An exact location in space |
| line segment | A part of a line that does not extend forever on either side |
Combine with other sets
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