| A | B |
|---|
| line | a straight path that extends without end in opposite directions |
| ray | a part of a line that starts at one endpoint and extends forever |
| plane | a flat surface that extends forever |
| line segment | a part of a line between two endpoints |
| equilateral triangle | a triangle with three congruent sides |
| acute triangle | a triangle with all angles measuring less than 90 degrees |
| obtuse triangle | a triangle containing one obtuse angle |
| right triangle | a triangle containing one right angle |
| parallelogram | a quadrilateral with two pairs of parallel sides |
| rhombus | a parallelogram with all sides congruent |
| diagonal | In a polygon, a segment that is drawn from one vertex to another and is not one of the sides of the polygon |
| side-side-side rule | A rule stating that if three sides of one triangle are congruent to three sides of another triangle, the triangles are congruent |
| transformation | a change in the size or position of a figure |
| image | a figure resulting from a transformation |
| translation | a movement of a figure along a straight line |
| rotation | a transformation in which a figure is rotated about a fixed point |
| reflection | a transformation of a figure that flips the figure across a line |
| line of reflection | a line that a figure is flipped across to create a mirror image of the original figure |
| line symmetry | a figure has this if one half is a mirror image of the other half |
| line of symmetry | the imaginary "mirror" in line symmetry |
| asymmetry | not identical on either side of a central line, not symmetrical |
| rotational symmetry | a figure has this if it can be rotated less than 360 degrees around a central point and coincide with the original figure |
| center of rotation | the point about which a figure is rotated |
| congruent | having the same shape and size |
| rectangle | a parallelogram with four right angles |
| square | a rectangle with four congruent sides |
| trapezoid | a quadrilateral with exactly one pair of parallel sides |
| kite | a quadrilateral with two pairs of adjacent congruent sides |
