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 line segment | is part of a line and has 2 endpoints |
| ray | part of a line that has one endpoint and extends forever in one direction |
| parallel lines | never cross and stay the same distance apart |
| intersecting lines | pass through the same point |
| perpendicular lines | intersecting lines that form square corners |
| point | an exact location in space |
| line | a straight path of points that goes on forever in two directions |
| plane | an endless flat surface |
| acute angle | has a measure of less than 90 degrees |
| right angle | has a measure of 90 degrees |
| obtuse angle | has a measure greater than 90 degrees |
| straight angle | has a measure of 180 degrees |
| vertex | the common endpoint of two rays or line segments |
| Complementary Angle | 2 angles that equal a right angle 90 degrees |
| Supplementary Angles | 2 or more angles that equal a straight angle 180 degrees |
| polygon | a closed plane figure made up of line segments |
| regular polygon | has sides of equal length and angles of equal measure |
| triangle | a 3 sided figure |
| quadrilateral | a 4 sided figure |
| pentagon | a 5 sided figure |
| hexagon | a 6 sided figure |
| octagon | an 8 sided figure |
| equilateral triangle | all 3 sides are the same length |
| isosceles triangle | 2 sides of the same length |
| scalene triangle | no sides have the same length |
| acute triangle | has 3 acute angles |
| obtuse triangle | has one obtuse angle |