| A | B |
|---|
| acute angle | An angle with a measure greater than zero degrees but less than 90 degrees. |
| angle | Two rays with a common endpoint. |
| complementary | Two angles whose measures have a sum of 90 degrees. |
| congruent | Having the same measure. |
| congruent figures | Figures that are the same shape and size. |
| corresponding parts | The parts of congruent figures that match. |
| degree | The most common unit of measure for angles. |
| equilateral triangle | A triangle having all three sides congruent and all three angles congruent (all angles equal 60 degrees). |
| heptagon | A polygon having seven sides. |
| hexagon | A polygon having six sides. |
| isosceles triangle | A triangle in which at least two sides are congruent. |
| line of symmetry | A line that divides a figure into halves that are reflections of each other. |
| line symmetry | Figures have this when two halves of the figure match. |
| obtuse angle | An angle that measures greater than 90 degrees but less than 180 degrees. |
| octagon | A polygon having eight sides. |
| parallelogram | A quadrilateral that has both pairs of opposite sides congruent and parallel. |
| pentagon | A polygon having five sides. |
| perpendicular | Two line segments that intersect to form right angles. |
| polygon | A simple closed figure in a plane formed by three or more line segments. |
| quadrilateral | A polygon with four sides. |
| rectangle | A parallelogram with four right angles. |
| rhombus | A parallelogram with all sides congruent. |
| right angle | An angle that measures exactly 90 degrees. |
| rotational symmetry | A figure has this if it can be turned or rotated less than 360 degrees about a fixed point so that the figure looks exactly as it did before being turned. |
| scalene triangle | A triangle in which no sides are congruent. |
| side | A ray that is part of an angle. |
| similar figures | Figures that have the same shape but different sizes. |
| square | A parallelogram with four congruent sides and four right angles. |
| straight angle | An angle that measures exactly 180 degrees. |
| supplementary | Two angles whose measures have a sum of 180 degrees. |
| triangle | A polygon having three sides. |
| vertex | The common endpoint of the two rays that form an angle. |
| trapezoid | A quadrilateral with EXACTLY one pair of opposite sides parallel. |
