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Unit 3 Geometry
Lines, Angles, and Reflections
| Term | Definition |
|---|---|
| reflection | a flip of a geometric figure |
| rotation | a turn of a geometric figure |
| reflective symmetry | the property of a figure that can be folded along a line so that the two halves match exactly |
| rotational symmetry | the property of a figure that can be turned less than 360 degrees and be identical with itself. |
| acute angle | an angle that has a measure less than 90 degrees |
| right angle | an angle that has a 90 measure |
| obtuse angle | an angle that has a measure more than 90 degrees and less than 180 degrees |
| perpendicular lines | lines that intersect to form a right angle |
| line of symmetry | a line that divides a figure into two mirror images |
| straight angle | an angle whose measure is 180 degrees |
| parallel lines | two or more lines that are always the same distance apart and never intersect no matter how far they are extended |
| zero angle | an angle whose measure is zero degrees |
| degree | a unit for measuring the size of angles |